This file was created by scanning the printed publication.

Text errors identified by the software have been corrected;

however, some errors may remain.
Editors SHARON E. CLARKE is a geographer and GIS analyst, Department of Forest

Science, Oregon State University, Corvallis, OR 97331; and SANDRA A. BRYCE

is a biogeographer, Dynamac Corporation, Environmental Protection Agency,

National Health and Environmental Effects Research Laboratory, Western Ecology

Division, Corvallis, OR 97333. This document is a product of cooperative research

between the U.S. Department of Agriculture, Forest Service; the Forest Science Department, Oregon State University; and the U.S. Environmental Protection Agency.

Cover Artwork Cover artwork was designed and produced by John Ivie.
Abstract Clarke, Sharon E.; Bryce, Sandra A., eds. 1997. Hierarchical subdivisions of the

Columbia Plateau and Blue Mountains ecoregions, Oregon and Washington. Gen.

Tech. Rep. PNW-GTR-395. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station. 114 p.

This document presents two spatial scales of a hierarchical, ecoregional framework

and provides a connection to both larger and smaller scale ecological classifications.

The two spatial scales are subregions (1:250,000) and landscape-level ecoregions

(1:100,000), or Level IV and Level V ecoregions. Level IV ecoregions were developed

by the Environmental Protection Agency because the resolution of national-scale

ecoregions provided insufficient detail to meet the needs of state agencies for establishing biocriteria, reference sites, and attainability goals for water-quality regulation.

For this project, two ecoregions—the Columbia Plateau and the Blue Mountains—

were subdivided into more detailed Level IV ecoregions. Similarly, the finer scale

landscape-level ecoregions (Level V) were developed to address local land management issues. The landscape-level ecoregions for northeast Oregon and southeast

Washington were created specifically to address the issue of anadromous fish habitat. Their delineation, however, employed landscape information similar to that used

in other levels of the ecoregion hierarchy, thereby indicating the potential for general

application of these regions to both terrestrial and aquatic research questions. The

study area for the landscape-level ecoregions was defined by contiguous watersheds

within the ecoregions of the Columbia Plateau and Blue Mountains to merge the

ecoregional information with units corresponding to fish distribution.

Keywords: Ecoregions, anadromous fish habitat, fish habitat, watershed classification,

landscape ecology, water quality, environmental mapping, classification.
Contents

10 Section 1—Level IV Ecoregipns of the Columbia Plateau

Ecoregion of Oregon, Washington, and Idaho

by Sandra A. Bryce and James M. Omernik

10 Columbia Plateau Ecoregion-Subregion Project

10 Description of the Columbia Plateau Ecoregion

12 Materials

13 Ecoregion Boundary Decisions

14 Description of the Columbia Plateau Subregions

20 Water Resource Issues of the Columbia Plateau Ecoregion

22 Literature Cited

24 Section 2—Level IV Ecoregions of the Blue Mountains Ecoregion of Oregon, Washington, and Idaho

by Sandra A. Bryce and James M. Omernik

24 Climate

25 Geology—The Birth of the Blues

27 Blue Mountains Soils

28 Blue Mountains Vegetation

34 Descriptions of the Blue Mountains Subregions

52 Literature Cited

56 Section 3—Landscape-Level Ecoregions for Seven Contiguous Watersheds, Northeast Oregon and Southeast Washington

by Sharon E. Clarke, Mark W. Garner, Bruce A. Mclntosh,

and James R. Sedell

56 Introduction

58 Objectives of the Project

59 Connection to Other Approaches

61 Rationale for Delineating Landscape-Level Ecoregions

68 Delineation of Landscape-Level Ecoregions

99 Conclusion

101 Literature Cited

114 Acknowledgments
Introduction Much of our disagreement about the proper role and function of regions,

models and other generalizations probably should be attributed to basic and

inherent differences between humans and their need for order, in which case

it cannot be resolved by rational discussion. Most of us are probably somewhere on a continuum between two polar extremes. At one extreme are

those tidy-minded souls whose instincts tell them that the world should move

with all the precision of a finely tuned watch,. . .that our inability to detect

regularity and order reflects our own weak analytical skills rather than the

possibility that it may not exist. At the other extreme are those rambunctious

types who perceive the world as a massive stochastic process, who glory in

its disorder, chaos, and complexity, and who revel in the thought that every

leaf on every tree is different. This battered old planet has quite enough

evidence to keep both extremes happily convinced that they are right.

John Fraser Hart, 1982

Background The condition of the ecosystems of the Columbia Plateau and Blue Mountains is presently the focus of several Federal and State agencies. One hundred and fifty years of

intensive land use—logging, road building, mining, grazing, and fire suppression—

have transformed forests and grasslands, threatening the existence and long-term

productivity of native ecosystems (Johnson and others 1994). Plans for restoration

include more holistic management of forest, range, and water resources.

Although the concept of ecosystem management has gained acceptance among land

management agencies, implementing it can be a challenge. It is difficult for resource

managers to apply the results of many individual studies to broad areas. Different

agencies have conflicting missions, overlapping jurisdictions, and administrative

boundaries that restrict an ecosystem focus overall. Resource managers in Canada

have experienced the same difficulties; they have stressed the importance of an ecosystem perspective, arguing that the bulk of environmental research is concentrated

on single-issue and single-medium subjects (Omernik 1995).

How do we move spatially and conceptually from single-issue research to consider

cumulative stresses and ecosystem response? To coordinate ecosystem management in environmental research, Federal land management agencies formed an interagency task force to draft a memorandum of agreement that promotes the use of a

common, hierarchical ecosystem framework. Existing ecoregion frameworks (Bailey

1983; Bailey and others 1994; Omernik 1987, 1995) provide the template for a common framework by delineating areas of similar landscape characteristics that reflect

the similarities in ecosystem type. By using a scheme that divides the landscape

ecologically rather than administratively, agencies will be better able to develop

strategies that are focused, ecologically significant, and thus, more cost-efficient.

Federal agencies already have invested much time and effort in developing their own

frameworks for particular objectives. It will be an arduous process to agree on a

common scheme; but if successful, it will be an important step toward coordinating

research efforts.

1
Recent movement toward ecosystem management within Federal land management

agencies has been prompted in large part by biological-diversity issues in forests of

the Pacific Northwest. After President Clinton’s April 1993 Forest Conference in

Portland, Oregon, various Federal agencies proposed initiatives to address problems

with endangered species, remnant old-growth forests, poor forest health, and declining anadromous fish runs. The Eastside Forest Ecosystem Health Assessment

and the Eastside Scientific Panel have addressed similar forest problems in eastern

Washington, Oregon, Idaho, Montana, and northern California (Everett and others

1993, Henjum and others 1994).

The interagency Forest Ecosystem Management Assessment Team (FEMAT) report

(FEMAT 1993) lists four components of an Aquatic Conservation Strategy: the establishment of riparian reserves and watershed refugia, and watershed analysis as a

foundation for watershed restoration. Ecoregion classifications at state and landscape

scales will contribute to all the components of the Aquatic Conservation Strategy by

identifying groups of watersheds that are similar in ecosystem structure and by

describing their expected condition.

A possible point of interagency contention is the tendency to consider watershed and

ecosystem frameworks as mutually exclusive approaches. As a framework for research and planning, ecoregions provide a natural complement to watersheds. Spatial

patterns in ecosystems or environmental resources continue across topographic

divides (Omernik and Griffith 1991). In addition, streams may pass through multiple

ecoregions, and their watersheds often change dramatically in character from headwaters to midstem to lowland sections. Figure 1 is an example of the interplay between ecoregions and watersheds (Bryce and Clarke 1996). Because streams B and

C are within the same ecoregion, they will have more in common than stream B has

with stream A. Although streams A and B are located within the same watershed,

they flow through distinctly different landscape types.

Data that offer no particular patterns when stratified by watershed may show patterns

when stratified by ecoregion. Both frameworks should be applied for a full exploration

of spatial patterns and management options; however, neither framework should be

stretched beyond its ability to explain variability and patterns in the data (Bryce and

Clarke 1996).

In this document, we report on the development and application of ecoregions at the

two highest resolution levels of the five-level hierarchy developed at the U.S. Environmental Protection Agency (EPA; Omernik 1995). Levels I and II classify ecosystems

on a continental scale for the North American Continent. Level III represents nationalscale ecoregions for the United States. Level IV regions are the more detailed

ecoregions for state-level applications, and Level V are the most detailed ecoregions

for landscape-level or local level projects. Further discussions of the development of

this ecoregion framework may be found in Bryce and Clarke (1996), Clarke and

others (1991), Gallant and others (1989), and Omernik (1987, 1995).

2
Figure1—Example of the interplay between ecoregions and watersheds.

3
Figure1—Example of the interplay between ecoregions and watersheds.

4
Ecoregion Methods Ecological regionalization is a form of spatial classification, the process by which

boundaries are drawn around relatively homogeneous areas at a specific scale or

level of detail. Ecoregions are developed through an iterative process that involves

map analysis, the collaboration of regional experts, an extensive literature review,

and a final integration of all available information. Physical characteristics such as

climate, geology, geomorphology, historical and present-day vegetation, soil, land

use, and hydrology are studied to determine the factors that reflect ecosystem

character.

Map analysis is but one aspect of this approach. An extensive literature review adds

an understanding of regional-level ecosystem processes and guides establishment of

map units. Collaboration with regional experts from State and Federal agencies and

academia also is essential to the process. This collaboration has the dual benefit of

introducing field experience into the process and allowing input from those who might

use the final product.

Finally, it is up to the geographer to integrate this disparate information. Many critical judgments are made based on research and experience. The product is not the

result of a mechanical overlay of maps; the computerized geographic information

system (GIS) is merely a tool to aid in analysis and final display. The final ecoregion

map is an interpretation or model of reality. Boundary decisions may result from a

different suite of landscape characteristics from one area of a region to another, depending on the shifting dominance of the landscape characteristics. Some of the

boundaries represent present-day conditions, but some represent conditions that no

longer exist. Modeling the historic condition has applications for distinguishing how

far human impacts have taken the ecosystem from a more unmanaged condition.

Discussions of individual boundary decisions in the chapters to follow will further

address this issue.

The ecoregion delineation is completed by drawing lines directly onto 1:250,000- or

1:100,000-scale topographic maps for digitization, correcting for topography where

appropriate to produce a precise line. An additional map has been developed that

depicts the boundary transition widths (a “fuzzy boundaries” map) (Clarke and others

1991, Griffith and others 1994). An example of a fuzzy boundary map of the Columbia

Plateau Levels III and IV ecoregions is shown in figure 2.

Applications of the Because they are constructed through the use of many data sources, ecoregions do

Ecoregion Framework not have a specific theme, and thus, they have the potential for general application.

to Resource Although they may not explain the response of any single ecological element, such

Management as a particular species distribution, they do represent an area of relative homogeneity

in landscape characteristics (Bryce and Clarke 1996). The ecoregion framework is an

organizational tool that may enable resource managers to apply an ecosystem approach to assessment, monitoring, and research, and thus transcend administrative

boundaries. Several of the most widely used applications of ecoregions are listed

below.

Sampling design—To plan a monitoring program, there may be a need to group

a population of similar sites together from which a representative sample may be

chosen. The size and heterogeneity of a region indicates the appropriate number

of sites required to adequately represent an area. Fewer sites per unit area will be

needed in homogeneous landscapes and more in heterogeneous landscapes.

Identification of ecoregions aids in determining the density of the sampling frame

to ensure that important areas are not missed.

5
Figure2—A boundary transition-width map included with the ecoregion-subregion map for the Columbia Plateau.

6
Ecoregions tend to run laterally across large topographic basins, particularly in mountainous areas. The headwaters, midstem, and mainstem of larger streams and rivers

may traverse different terrain types represented by unique ecoregions (fig. 1). To capture the range of conditions, sites from multiple watersheds within each ecoregion can

be grouped. Though no two sites are exactly alike in physical characteristics or quality, a group of sites within an ecoregion tends to be similar.

With a hierarchical regional framework, the scale of ecoregion may be chosen to fit

a particular project. Ideally, the scale should fit the type of data being gathered, the

spatial extent of sampling, and the research questions being asked.

Data analysis—Stratifying sites and sampling information into relatively homogeneous groups reduces apparent variability and increases precision in data analysis.

Once the regional boundaries have been shown through field testing to be representationally accurate, the regions provide a defensible area in which site-specific results

may be extrapolated. In this way, local project results may be applied to broader

scale resource management. Ecoregions lend a predictive capacity to management

decisions through the assumption that a subpopulation of sites within a relatively

homogeneous region will respond similarly to a specific type of management.

Water-quality standards—Ecoregions have been used by states to structure their

water-resource monitoring and assessment programs (Heiskary and Wilson 1989,

Larsen and others 1988, Rohm and others 1987). With a spatial framework, water resource managers are able to set regionally appropriate management goals for lakes

and streams and design programs for nonpoint-source pollution abatement and reduction of effluent discharges. Setting water-quality standards regionally means that

streams are less likely to be either overprotected or underprotected as they may

with a single nationwide or statewide standard.

Reference condition and ecosystem restoration—Ecoregions provide a framework

for locating water bodies to serve as reference sites. Reference sites can be chosen

from within any scale in the ecoregion hierarchy. As a benchmark for attainable conditions, a reference site should be both regionally representative and relatively undisturbed (Gallant and others 1989, Hughes and others 1986). Reference areas,

chosen within a regional framework, are representative of a particular population of

streams and serve as a model of attainable condition. Until now, management of

water resources has been the focus of the regional reference site concept. With the

increasing interest in ecosystem management, however, there is an opportunity to expand the implementation of the concept to relatively undisturbed terrestrial sites representative of the landscape character of the ecoregion.

Rehabilitation of disturbed sites can proceed most effectively if there is a measurable

goal represented by the reference site, even if that goal is not completely attainable.

Other sites of different disturbance can be compared with this model and ranked

along a continuum of condition. Relating present condition to the potential capability

of the systems contributes to the search for the probable causes of condition. Once

probable causes of degradation are identified, managers can set priorities for costeffective restoration.

‘ Personal communication. 1995. J. Omernik, research

geographer, U.S. Environmental Protection Agency, National

Health and Environmental Effects Laboratory, Western

Ecology Division, Corvallis, OR 97333.

7
Scope of Work This introductory section presented the rationale and methods used in the ecoregion

process as well as applications of the ecoregion framework. The next two sections

describe Level IV ecoregions displayed in the accompanying maps for the Columbia

Plateau and Blue Mountains ecoregions. Photographs in insert A depict the Level IV

ecoregions. The complexity and relative importance of factors considered in the

development of ecoregions differed greatly between these two ecoregions. The same

landscape characteristics were considered in each ecoregion project, but different combinations of factors tended to dominate depending on the character of the

region. For example, the landscape of the Columbia Plateau is a product of a dramatic series of events during the Pleistocene (Bretz 1969). Its ecosystems are a reflection of the arid climate, soil, glacial geomorphology, and fluvial erosion. The clarity

of these features made the regionalization of the Columbia Plateau relatively straightforward. The greater difficulty there arises from applying an ecosystem framework to

an intensively farmed, largely privately owned, arid region. In the Blue Mountains, on

the other hand, the dominant factors are climatic and elevational gradients imposed

on an extremely complex geology; the complexity of the landscape and the general

lack of biological, geological, and climatic information, particularly for higher elevations, makes this project a first iteration of an ongoing refinement of ecological

regions there.

Section 3 describes the development of landscape-level ecoregions (Level V) for

seven contiguous watersheds in northeastern Oregon and southeastern Washington

located within both the Columbia Plateau and Blue Mountains ecoregions. The

Bonneville Power Administration (BPA) is required by law to restore anadromous fish

runs to compensate for fish losses incurred at dams on the Columbia River (Pacific

Northwest Electric Power Planning Act 1980). The BPA funded this project to develop

landscape-level ecoregions to help define expected habitat conditions. The project is

an effort to stratify a complex area into more homogeneous units that may have

similar potentials and reactions to stressors. In this section, we outline the connection between stream-habitat characteristics and landscape characteristics, and we

describe how each of the major landscape characteristics might affect fish habitat.

Insert A illustrates the connection between the Level IV and Level V ecoregion hierarchy. The photos on the left and at the bottom of the page depict the Level IV ecoregions of the Columbia Plateau and Blue Mountains. To demonstrate the variability

within these subregions, represented by landscape-level ecoregions (Level V), the

photos on the top right show the diversity within the Maritime subregion, and those at

center right show the diversity within the Canyons and Dissected Highlands

subregion.

The landscape-level ecoregions described in section 3 were developed specifically

for anadromous fish habitat research and management (Bryce and Clarke 1996). The

methods and types of data sources, however, are the same as those used in ecoregion delineation at broader scales in the hierarchy. For this reason, we believe the

classification may have broader application to other resource issues. The full complement of regions at a particular scale may not be necessary for a specific project; regions may be aggregated depending on the objectives of the project. The rationale

for making boundary decisions has been discussed in detail, which should help in

assessing the usefulness of the classification for other resource issues.

8
Literature Cited Bailey, R.G. 1983. Delineation of ecosystem regions. Environmental Management.

7: 365-373.

Bailey, R.G.; Avers, P.E.; King, T.; McNab, W.H., eds. 1994. Map of ecoregions

and subregions of the United States. Washington, DC: U.S. Department of

Agriculture, Forest Service. 1:7,500,000.

Bretz, J.H. 1969. The Lake Missoula floods and the Channeled Scablands. Journal

of Geology. 77: 505-543.

Bryce, S.A.; Clarke, S.E. 1996. Landscape-level ecological regions: linking

state-level ecological frameworks with stream habitat. Environmental Management.

20(3): 297-311.

Clarke, S.E.; White, D.; Schaedel, A.L. 1991. Oregon, USA, ecological regions and

subregions for water quality management. Environmental Management. 15(6):

847-856.

Everett, R.E.; Hessburg, P.; Jensen, ML; Bormann, B. 1993. Eastside forest

ecosystem health assessment. Volume I: Executive summary. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Region; Pacific

Northwest Research Station. 57 p.

Forest Ecosystem Management Assessment Team [FEMATJ. 1993. Forest ecosystem management: an ecological, economic, and social assessment. Portland,

OR: U.S. Department of Agriculture; U.S. Department of the Interior [and others].

[Irregular pagination].

Gallant, A.L.; Whittier, T.R.; Larsen, D.P. [and others]. 1989. Regionalization as a

tool for managing environmental resources. EPA/600/3-89/060. Corvallis, OR: U.S.

Environmental Protection Agency, Environmental Research Laboratory. 152 p.

Griffith, G.E.; Omernik, J.O.; Wilton, T.F.; Pierson, S.M. 1994. Ecoregions and

subregions of Iowa: a framework for water quality assessment and management.

Journal of the Iowa Academy of Sciences. 10(1): 5-13.

Hart, J.F. 1982. The highest form of the geographer’s art. Annals of the Association

of American Geographers. 72: 1-29.

Henjum, M.G.; Karr, J.R.; Bottom, D.L. [and others]. 1994. Interim protection for

late-successional forests, fisheries, and watersheds: national forests east of the

Cascade crest, Oregon and Washington. Bethesda, MD: The Wildlife Society.

245 p.

Heiskary, S.A.; Wilson, C.B. 1989. The regional nature of lake water quality across

Minnesota: an analysis for improving resource management. Journal of Minnesota

Academy of Sciences. 55(1): 71-77.

Hughes, R.M.; Larsen, D.P.; Omernik, J.M. 1986. Regional reference sites: a

method for assessing stream potentials. Environmental Management. 10: 629-635.

9
Johnson, C.G., Jr.; Clausnitzer, R.R.; Mehringer, P.J.; Oliver, C.D. 1994. Biotic

and abiotic processes of eastside ecosystems: the effects of management on plant

and community ecology, and on stand and landscape vegetation dynamics. Gen.

Tech. Rep. PNW-GTR-322. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station. 66 p. (Everett, Richard L, assessment team leader; Eastside forest ecosystem health assessment; Hessburg,

Paul F., science team leader and tech. ed., Volume III: assessment).

Larsen, D.P.; Dudley, D.R.; Hughes, R.M. 1988. A regional approach to assess

attainable water quality: an Ohio case study. Journal of Soil and Water

Conservation. 43(2): 171-176.

Omernik, J.M. 1987. Ecoregions of the conterminous United States. Annals of the

Association of American Geographers. 77(1): 118-125. (text and map

supplement).

Omernik, J.M. 1995. Ecoregions: a spatial framework for environmental management. In: Davis, W.S.; Simon, T.P., eds. Biological assessment and criteria: tools

for water resource planning and decision making. Ann Arbor, Ml: Lewis

Publishers: 49-65.

Omernik, J.M.; Griffith, G.E. 1991. Ecological regions versus hydrologic units:

frame works for managing water quality. Journal of Soil and Water Conservation.

46: 334-340.

Pacific Northwest Electric Power Planning and Conservation Act. Act of Dec. 5,

1980. 94 Stat. 2697. 16 U.S.C. 839-839H.

Rohm, C.M.; Giese, J.W.; Bennett, C.C. 1987. Evaluation of an aquatic ecoregion

classification of streams in Arkansas. Journal of Freshwater Ecology. 41(1):

127-140.

10
Section 1—Level IV Ecoregions of the

Columbia Plateau Ecoregion of Oregon,

Washington, and Idaho

by Sandra A. Bryce and James M. Omernik1

Columbia Plateau The impetus for the Columbia Plateau regionalization project was a mutual concern

Ecoregion-Subregion of EPA Region 10, the Washington Department of Ecology, and the Oregon DepartProject2 ment of Environmental Quality to better frame management decisions about nonpoint

source pollution. The agencies also agreed that the refinement of ecoregion lines,

the delineation of subregions (Level IV ecoregions), and the selection of reference

sites were prerequisites for establishing biocriteria standards in portions of Oregon,

Washington, and Idaho. An ecosystem-based framework also afforded the opportunity

for the three states to share data and assessment results in regions of similar natural

capacities. Although the original project had a water quality focus, ecoregions are

delineated by using terrestrial landscape information; thus, they have the potential for

terrestrial applications as well.

Although geographers at the National Health and Environmental Effects Laboratory,

Western Ecology Division (NHEERL-WED) of EPA in Corvallis, Oregon, were responsible for the final delineation of ecoregion boundaries, the Columbia Plateau

project was a collaborative effort with State resource managers and regional experts.

Meetings and phone consultations were held with State and Federal agency personnel and members of academia to review progress and exchange ideas. Such qualitative input was critical to the creation of a regional framework that will be meaningful

to those using it. Continued collaboration also is necessary for the evaluation of the

boundaries derived from the geographic data.

Description of the The arid nature and earth-toned landscape of the Columbia Plateau belies the

Columbia Plateau spectacular origins of its topography. The Columbia Plateau was shaped by episodic

Ecoregion geologic events of epic proportions. During the Miocene epoch, between 17 and

6 million years ago, lava flows erupted from vents in southeastern Washington and

northeastern Oregon to fill the basin with lava up to 3.2 kilometers (2 mi) thick. As

many as 200 separate flows eventually covered an area of about 160,000 square

kilometers (61,776 mi2

) (Baker and others 1991). Earth’s crust gradually sank under

the weight of the lava, producing the sloping Columbia Plateau (Allen and others

1986). During the Pleistocene, a continuous covering of loess was aerially deposited

over the basalt. Because of the general saucer shape of the area, sloping from its

edges to the low point in the Pasco basin, the Columbia Plateau is often called the

Columbia basin. Because the term “basin” also indicates drainage, however, we

hereafter call the region the Columbia Plateau ecoregion.

‘JAMES M. OMERNIK is a research geographer,

Environmental Protection Agency, National Health and

Environmental Effects Research Laboratory, Western

Ecology Division, Corvallis, OR 97333.

2 Ecoregion terminology evolved during the time that this

document was in press. The terms national-level ecoregions,

subregions, and landscape-level ecoregions have been

replaced by Level III, Level IV, and Level V ecoregions.

11
The features on the surface of the plateau were sculpted during the Pleistocene.

Those features that are most discernible are thought to have occurred between

12,000 and 15,000 years ago during the last advance of continental glaciers (Allen

and others 1986). Periodically during this time, the Clark Fork River in Montana was

dammed by a lobe of the glacier, forming the huge Lake Missoula, which covered

4825 square kilometers (3,000 mi2) of intermountain valleys in Montana. Rising

waters regularly breached the ice dam, sending huge quantities of water surging

across the Columbia Plateau. These floods differed in intensity, but the largest are

said to have contained up to 10 times the flow of all rivers in the world or 60 times

the flow of the Amazon River (Allen and others 1986, USDI Geological Survey 1982).

The flood channels cut through the thick deposits of windblown soil, leaving islands

of loess separated by scablands and bedrock channels.

Attributing the topography of the plateau to massive flood events was the painstaking

and controversial life work of geologist J. Harlan Bretz (1969), who crossed much of

the scabland country on foot, mapping as he went and piecing together the evidence

of the Missoula floods (Allen and others 1986). What took Bretz 40 years to compile

we can now visualize in an instant with the aid of satellite imagery—the mammoth

braided channels crossing the entire plateau from northeast to southwest.

The Columbia Plateau is an arid shrub-grassland surrounded on all sides by forested

mountain ranges: the Cascade Range to the west, the Okanogan Highlands to the

north, the Blue Mountains to the south, and the Rocky Mountains to the east. The

climate of the Columbia Plateau is continental with a marine influence. Summers are

hot and dry; most of the precipitation falls during winter. Precipitation increases

across the plateau from southwest to northeast. It is lowest in the basins on the

western side of the plateau, where the rain-shadow effect of the Cascade Range

limits precipitation to 15.2 to 22.9 centimeters (6 to 9 in) per year. Rainfall gradually

increases to the east with higher elevations and proximity to the Rocky Mountains

and Blue Mountains.

Temperature, moisture, and mineral content determine soil formation, and the texture

affects the rate at which complex soil horizons, organic matter, and clay layers develop (Beieler 1981). The lack of moisture on the Columbia Plateau results in soil low

in organic matter and clay. Depending on their location, soils of the Columbia Plateau

may be derived from basalt colluvium on hillslopes and canyon walls, alluvium from

valley floors, or gravelly flood deposits and glacial outwash. However, the predominant soil of the plateau is loess. Loess forms a large deposit called the Palouse Formation that covers the entire area of the Columbia Plateau to depths of 75 meters

(22.9 ft) in the southeastern Palouse Hills (Baker and others 1991). It is of granitic

and metamorphic origin, transported by glaciers from the Rocky Mountains to the east

and north and redeposited by prevailing southwesterly winds over the past 50,000

years (Baker and others 1991, Beieler 1981).

Gradually increasing precipitation toward the northeast influences the dryland agricultural capability of the loess soil. Cropping techniques differ from a 2-year winter wheat

and fallow rotation in areas with 22.9 to 38.1 centimeters (9 to 15 in) per year of precipitation (9 to 15 in) to a 3-year rotation of winter wheat, spring barley, and fallow in

areas receiving 38.1 to 45.7 centimeters (15 to 18 in) per year of precipitation

(Stockman 1981). Annual cropping on unirrigated land is practiced only in the Palouse

Hills, where moisture levels reach 45.7 to 58.4 centimeters (18 to 23 in) per year.

Loess is highly productive, but it is also highly erosive. In the heart of the Palouse

12
River basin, farming on steep slopes and farming practices such as clean tilling fallow

fields leads to average erosion rates of 44.8 tons per hectare (20 tons per acre)

through rill and sheet erosion during the wet season (Steiner 1987).

The type and amount of vegetation of the Columbia Plateau also differs with temperature and moisture. The low precipitation amounts and negligible yearly runoff combined with high evapotranspiration and deep, dry loessial soil create an environment

ill suited to tree growth. Though the plateau has been called a desert, Daubenmire

(1970) describes it as a steppe. He defines a desert as a region too dry to support

grassland and a steppe as a region with enough moisture to support grasses but not

trees. According to this definition, the Columbia Plateau is a grassland steppe.

Daubenmire has divided the plateau into nine vegetation zones. The big sagebrushbluebunch3

 wheatgrass and big sagebrush-Idaho fescue associations occur in the

driest core of the plateau. Grasses without the sagebrush element grow in the slightly

wetter eastern portion of the plateau. The other five associations appear around the

perimeter of the plateau in the lusher meadows of grasses, broad-leafed forbs, and

shrubs that form the transition to forest. The shrub element differs from bitterbrush in

the eastern Cascade foothills to snowberry species in the Rocky Mountain transition

zone.

There is no evidence that the plant life of the Columbia Plateau has evolved under

either a grazing or a fire regime. The bunchgrasses will tolerate light grazing after

seed formation. They do not recover after heavy grazing but are replaced by alien

grasses, such as cheatgrass (Bromus tectorum L). The brushy species, on the other

hand, are sensitive to fire. It is unlikely that large herds of grazing animals roamed

the plateau as they did the Great Plains or that the original inhabitants used fire as a

hunting strategy (Daubenmire 1970, Franklin and Dyrness 1988).

In summary, the Columbia Plateau differs from adjacent mountainous, forested

ecoregions in its aridity, low relief, and lack of trees. However, no single attribute described above, not geology, climate, topography, soil, or vegetation, is sufficient to

determine the ecoregion boundaries of the Columbia Plateau. For example, the flood

basalts that comprise the Columbia Plateau also form the foundation of the Blue

Mountains to the south. The Blue Mountains ecosystem is different from the Columbia

Plateau, yet large portions of it have the same geology. Consequently, geology is not

useful for making the southern ecoregion boundary decisions. Similarly, vegetation is

not a dominant feature in boundary decisions in the Deschutes River area of Oregon.

Similar vegetation associations occur just to the south in the high desert area of Oregon (as they do in southern Idaho and Montana). Producing a map of ecological regions requires integrating all the landscape characteristics and developing a rationale

for the boundaries that is consistent with the projected uses for the ecoregions. In

this way, ecoregion maps differ from thematic maps, which seek to define the distribution of a single characteristic.

Materials Component maps and data for the Columbia Plateau project were assembled from

the participating states, from EPA’s NEERL-WED map library, and from Oregon

State University’s map library. Additional information, such as historical documents,

satellite images, and pertinent published articles, contributed to the refinement and

evaluation of subregion boundaries.

3 Scientific names of tree and plant species are mentioned in

tables 1, 2, and 10.

13
The data that were most useful for the subdivision of the Columbia Plateau ecoregion

were maps of geology, soil, potential vegetation, topography, and land use-landcover.

Digital coverages at 1:250,000 scale from a series of soil maps (STATSGO) were

acquired from the USDA Soil Conservation Service (SCS) (Note: in late 1994, USDA

changed the name of SCS to the National Resources Conservation Service [NRCS]).

These maps were supplemented by existing county level 1:24,000-scale soil maps

and texts. A present-day vegetation map of Oregon sponsored by the USDI Fish and

Wildlife Service (FWS) also was available in digital form from the Idaho Department

of Water Resources. This map was supplemented with smaller scale maps of Oregon

and Washington vegetation and literature about the vegetation communities of the

plateau. Geological information was provided by a 1:500,000-scale map of Oregon,

both digital and hard copy (Walker and McLeod 1991) and 1:250,000-scale geologic

maps of the northeast and southeast quadrants of the State of Washington4 (Stoffel

and others 1991). Land use maps from the U.S. Department of the Interior, Geological Survey (GS) were available in digital form. Finally, at 1:250,000- and 1:100,000-

scale, GS topographic maps were indispensable for the interpretation of land surface

form, drainage pattern, contour intervals, gradient, aspect, and elevation. Topographic

maps serve as a reality check for the other maps, especially those that have been

interpreted, such as the soil, geology, and vegetation maps. The ecoregion boundaries were delineated and digitized by using the 1:250,000-scale topographic maps

as base maps.

Ecoregion Boundary During the regionalization process, some boundaries between distinctive ecoregions

Decisions or subregions appear obvious, whereas others are more difficult to determine. For

example, the Channeled Scablands subregion of the Columbia Plateau is determined

by the clearly visible boundaries of flood channels gouged out of the landscape.

Other boundaries are not so readily apparent; their delineation requires an accompanying rationale, which is the result of integrating the multiple source materials.

These less apparent boundaries, such as those at the change from grassland to

forest at the perimeter of the plateau, represent transition areas of various widths

along ecological gradients. One method of mapping this phenomenon is through the

use of “fuzzy boundaries” (Clarke and others 1991). A boundary transition width map

is included with the ecoregion-subregion map for the Columbia Plateau (fig. 2). Sites

near region boundaries, especially in transition areas, tend to have characteristics of

both regions. Field visits are necessary to determine which regional characteristics

dominate at sites of interest.

Other boundary considerations arise because of variations in the extent that human

activities have changed the landscape. To have boundaries represent relatively

constant conditions, ecological regions are defined by potential capability. As

Daubenmire found when trying to relate the distribution of vegetation to climate

patterns (Daubenmire 1956), the correlations between climate and vegetation are

meaningful only where vegetation boundaries are relatively stable. He knew that

fossil-pollen studies indicated that little climate-induced change had occurred in plant

distributions since the end of the last glacial advance; however, the high frequency of

human changes and the extirpation of species confounded his search for patterns.

4 Schuster, J.E. [In preparation]. Draft geological map of

Washington-southeast quadrant (Scale 1:250,000).

14
Anthropogenic changes in the Columbia Plateau have continued unabated since

Daubenmire’s investigations in the 1950s. Large irrigation projects across the driest

parts of the plateau, once known as the “Great Inland Desert,” have markedly

changed the ground-water and surface-water patterns. Aeas irrigated with surface

water from the Columbia and Yakima Rivers are experiencing a dramatic increase

in the amount of ground water and excess irrigation runoff. For example, the extent

of marshland has greatly increased in the Potholes region near Moses Lake,

Washington. Long-term ground-water recharge estimates, covering the period

1956-77, for both predevelopment and modern land use conditions in the core area

of the Columbia Plateau, showed an increase of 5.7 centimeters (2.23 in) per year

on average in the rate of ground-water recharge. For the zone covering the Moses

Lake area, recharge increased from 1.45 centimeters (0.57 in) per year to 25.6 centimeters (10.07 in) per year. Conversely, in areas that are irrigated from wells, water

withdrawals have caused a decrease in recharge across the zone (Bauer and

Vaccaro 1990).

These dramatic changes have not been incorporated into the boundary decisions for

subregion lines. Although it is likely that wide areas of the Columbia Plateau will never

return to their original condition, we cannot gauge the extent of the human-induced

changes to ecosystems unless we use a model of the presettlement condition as a

guide. There is enough information available on temperature and precipitation regimes, soil, and native vegetation to reconstruct the boundaries of the presettlement

ecosystems. Human-caused changes, such as the modifications in ground water and

surface runoff in irrigated areas, or the dominance of cheatgrass and other alien

plants across the formerly discrete vegetation zones of the plateau, can be treated as

a separate layer of information, which is superimposed on the model of ecosystem

potential.

Description of the The ecoregions described below are presented in the map of the Columbia Plateau

Columbia Plateau subregions insert B. Native vegetation of the Columbia Plateau is listed in table 1.

Subregions

Channeled Scablands and Loess Islands—The Channeled Scablands (insert A,

10a; insert B, 10a) were formed as immense floods periodically broke through the ice

dams blocking glacial Lake Missoula during the Pleistocene. The immense quantity

and high speed of the surging water scoured away the loess covering the plateau as

well as portions of the underlying basalt bedrock. The vertical jointing of the basalt

makes it susceptible to “plucking.” This phenomenon can be seen in the steep vertical

walls of the flood channels, in the many small lakes, called kolk lakes, gouged out of

the basalt surface, and in the giant plunge pools created at huge cataracts. In the

northwest part of the plateau, the scabland channels, such as Grand Coulee and

Moses Coulee, also served as outflow channels for glacial Lake Columbia and the

Okanogan lobe of the Wisconsin ice sheet.

Patterned ground covers the basalt plateaus bordering the main flood channels.

These “scabs” are composed of mounds of loess surrounded by rock fragments.

The soil is a thin veneer 0 to 62.5 centimeters (0 to 25 in) on the basalt surface

of the scablands (Stockman 1981).

15
Table 1—Native vegetation defining Columbia Plateau subregions4

Subregion Genus species Common name

Channeled Scablands (10a) Artemisia rigida (Nutt.) Gray Stiff sage

Poa sandbergii Vasey Sandberg’s bluegrass

Loess Islands (10b) Artemisia tridentata (Nutt.) Big sage

Agropyron spicatum (Pursh) Scribn. & Smith Bluebunch wheatgrass

Festuca idahoensis Elmer Idaho fescue

Artemisia tripartita Rydb. Threetip sage

Umatilla Plateau (10c) Agropyron spicatum Bluebunch wheatgrass

Festuca idahoensis Idaho fescue

Rosa spp. Rose

Crataegus spp. Hawthorne

Symphoricarpus albus (L.) Blake Common snowberry

Okanogan Drift Hills (10d) Artemisia tridentata Big sage

Agropyron spicatum Bluebunch wheatgrass

Artemisia tripartita Threetip sage

Festuca idahoensis Idaho fescue

Purshia tridentata (Pursh) DC Bitterbrush

Pinus ponderosa Dougl. ex Laws. Ponderosa pine

Pleistocene Lake Basins (10e) Artemisia tridentata Big sage

Agropyron spicatum Bluebunch wheatgrass

Artemisia tripartita Threetip sage

Festuca idahoensis Idaho fescue

Purshia tridentata (Pursh) DC Bitterbrush

Pinus ponderosa Dougl. ex Laws. Ponderosa pine

Pleistocene Lake Basins (10e) Artemisia tridentata Big sage

Agropyron spicatum Bluebunch wheatgrass

Canyons and Dissected Uplands (10f) Rosa spp. Rose

Symphoricarpus albus Common snowberry

Yakima Folds (10g) Artemisia tridentata Big sage

Agropyron spicatum Bluebunch wheatgrass

Festuca idahoensis Idaho fescue

Hieracium spp. Hawkweeds

Purshia tridentata Bitterbrush

a By legend number in insert B.

16
Pleistocene Lake Basins—Vast temporary lakes formed periodically with the release

of flood waters from glacial Lakes Missoula and Columbia during the Pleistocene

(insert A, 10e; insert B, 10e). Lake Lewis formed from the damming of the Columbia

River at Wallula Gap on the southern Washington border, and covered 4825 square

kilometers (3,000 mi2

) of the Quincy and Pasco basins and Walla Walla and Yakima

River Valleys. Downriver, the flood waters ponded again at the entrance to the

Columbia Gorge, creating Lake Condon. High-water marks and faint shorelines mark

the margins of the lake basins at the 304- to 365-meter (1,000- to 1,200-ft) contour.

The water level at Yakima has been estimated at 61 meters (200 ft) above the present city. Ice-rafted erratic boulders have been found stranded on ridges surrounding

the basins (Allen and others 1986, Baker and others 1991). Flood waters, tearing

through the Channeled Scablands, dropped their load of loess, sand, and outwash

gravel in the basins. One of the largest flood-related features, the Priest Rapids bar,

formed downstream of Sentinel Gap and fills the basin north of Richland.

The lake basins are in the driest areas of the rain shadow of the Cascade Range,

receiving 15.2 to 30.5 centimeters (6 to 12 in) of precipitation per year. Native vegetation consists of the widespread big sagebrush-bluebunch wheatgrass association.

These sagebrush areas have been transformed by large irrigation projects that provide Columbia and Yakima River water via pump and canal. The synclinal Kittitas

Valley has been included in this subregion even though it was not part of glacial

Lake Lewis because of its position within the Yakima Folds subregion (insert B, 10g)

and because it has a similar lacustrine history, climate, soil, and land use capability.

Canyons and Dissected Uplands—In the Canyons and Dissected Uplands subregion (insert A, 10f; insert B, 10f) the Snake, Grande Ronde, Clearwater, Imnaha,

and Salmon Rivers and their tributaries have cut the plateau to depths of 610 to

1524 meters (2,000 to 5,000 ft). The canyons penetrate south into Oregon and divide

the Blue Mountains from the Rocky Mountains. The dissected portions of the plateau

differ from Palouse-like loess hills in the east and south of the Snake River near

Dayton or Pomeroy, Washington, to the sharp ridges near the Blue Mountains. In

northeastern Oregon, the Grande Ronde River canyon cuts laterally across the area

that is recognized as a major source of the lava flows that originally formed the

Columbia Plateau (Hooper and Reidel 1989).

Rainfall amounts in the subregion range from 25.4 to 58.4 centimeters (10 to 23 in)

per year depending on elevation. Native vegetation is diverse due to the proximity of

the Blue Mountains and Rocky Mountains and the wide range in precipitation. Pure

grasslands without a sagebrush component cover the subregion in its driest portions,

the 30.5 to 40.6 centimeters (12 to 16 in) per year precipitation zone. As the plateau

rises toward the Blue Mountains and the northern Rockies, a shrub component, either

rose or snowberry, is added to the association. Grazing and farming has eliminated

much of the original plant cover. The sharptailed grouse (Tympanuchus phasianellus),

once abundant in the fescue-snowberry zone, had disappeared completely

(Daubenmire 1970); but it recently has been reintroduced.

Yakima Folds—The Yakima Fold (insert A, 10g; insert B, 10g) belt is a series of

anticlinal ridges and synclinal valleys that covers 14 000 square kilometers (8,700

mi2

) of the western Columbia Plateau (Reidel and Campbell 1989). The folds

include Columbia, Rattlesnake, and Frenchmen Hills; the Saddle Mountains; and the

Umtanum, Yakima, and Manastash Ridges. The ridges are composed of layer upon

17
layer of basalt. Oil drilling in the Rattlesnake Hills reached depths of 3648 meters

(12,000 ft) without clearing basalt (Rasmussen 1971). The slow deformation of the

central plateau under tectonic influences as well as the immense weight of the flood

basalts caused a warping of the western end (Allen and others 1986, Baker and

others 1991). The uplift was slow enough to allow the Yakima River to retain its

meandering course through the folds.

The Yakima Folds lie in the rain shadow of the Cascade Range. Precipitation

amounts range from 15.3 centimeters at 30.5 meters (6 in at 500 ft) in elevation to

38.1 centimeters at 1067.5 meters (15 in at 3,500 ft) (Rasmussen 1971). The ridges

have steep north-facing slopes. Soil on the north side of the ridges is thin and derived from basalt. Depth to basalt ranges from 30.5 to 50.8 centimeters (12 to 20 in).

The gentle south-facing slopes are blanketed with loess to depths of 50.8 to 152.4

centimeters (20 to 60 in). Land use capability follows this pattern with dryland wheat

farming on the south side and grazing on the north side of Rattlesnake and Horse

Heaven Hills.

The plant cover of the driest portion of the subregion is the big sagebrush-bluebunch

wheatgrass association. It reaches elevations of 820 meters (2,690 ft) on the summits

of the eastern Yakima Folds. Other associations include fescue-hawkweed in the

Columbia Hills near Goldendale and a bitterbrush-fescue community in the east Cascade foothills just below the tree line north of Ellensburg and at the eastern end of the

Columbia Gorge. Elsewhere the big sagebrush and wheatgrass association occurs

right to the forest edge. Daubenmire theorized that the sagebrush-pine ecotone was

determined by the change in mean annual precipitation: never more than 36 centimeters (14.5 in) in the sagebrush zone and never less than 40.8 centimeters (16.5 in)

in the pine forest (Daubenmire 1956).

The synclinal valleys associated with the folds, such as the Yakima, Ahtanum, and

Kittitas Valleys, are discussed separately under the Pleistocene Lake Basins

subregion.

Palouse Hills and Nez Perce Prairie—The elliptical Palouse Hills subregion (insert

B, 10h) ranges from Spokane in the north to the edge of the Snake River canyon in

the south. The eastern boundary is determined by the transition to the granites of the

Rocky Mountains, increased precipitation (up to 55 cm [21-7 in]), and the transitional

forest soils. The change from the mesic Palouse soil to the drier Walla Walla soil, as

interpreted from county soil surveys, marks the western boundary. The loess-covered

area southeast of Moscow, Idaho, can be considered the easternmost extension of

the Palouse Hills. However, because this area is cut by deep canyons, tributaries to

the Snake and Clearwater Rivers, it was included in the Canyons and Dissected

Uplands subregion.

Rainfall in the Palouse Hills ranges from 40.6 to 58.4 centimeters (16 to 23 in) per

year. Because of the mesic conditions, the soils of the Palouse are classified as

Mollisols rather than Aridosols. They have a higher organic matter and clay content than other loessial soils on the plateau. In spite of the increased precipitation,

most of the runoff occurs in January and February, meaning that small, loessbottomed streams rising within the subregion are intermittent. The only perennial

streams originate from the Rocky Mountains to the east.

18
It has been suggested that the shape of the Palouse Hills results from a combination

of strong wind action from the southwest that formed sharp dunelike crests toward

the northeast and nivation cirques or amphitheaters caused by the accumulation of

snowdrifts on the north and east sides (Donaldson 1980). There is also evidence of

the eastward migration of the hill summits during drier times presumably caused by

wind action (Baker and others 1991).

The mesic fescue-snowberry plant association marking the transition through the

Rocky Mountains foothills has been almost entirely supplanted by wheat farms. Bits

of original vegetation survive in the “eyebrows” left where the land is too steep to

plow. The Palouse Hills are highly productive, producing up to 40.5 bushels of wheat

per hectare (100 bushels of wheat per acre) (Steiner 1987).

The Nez Perce Prairie—The Nez Perce Prairie (insert B, 10j) is a rolling loess plain

in western Idaho, southeast of the Palouse Hills. Though generally similar to the

Palouse region, it differs in having higher elevations overall, colder temperatures, and

higher precipitation levels. As a result, the loess soils have a higher clay development. Also, because the Nez Perce Prairie was out of the main path of aerial loess

deposition, the soil is shallower than in the Palouse Hills. The Prairie is bounded on

all sides by deep river canyons. The area east of Joseph and Enterprise in northeast

Oregon is sometimes included with the Nez Perce Prairie (Raisz 1965, Steiner 1987,

USDA Soil Conservation Service 1986). Because of its even thinner loess cover,

lower precipitation, and proximity to the Snake River canyon, however, it has been

included with the Canyons and Dissected Uplands subregion.

Deep Loess Foothills—The Deep Loess foothills (insert A, 10i; insert B, 10j) of

the Blue Mountains follow an arc on the northwest slopes beginning just north of

Pendleton. The subregion could be a disjunct portion of the Palouse Hills, as it has

Palouse soil, the same range in precipitation (40.6 to 58.4 centimeters [16 to 23 in]

per year), and similar land use capability with annual cropping possible. The differences lie in the topography, physiography, and hydrography. The dunelike ridges

of the Palouse Hills are replaced by terraced ridges rising to the forested Blue Mountains. The sloping basalt ridges are bisected by perennial streams fed by the higher

rainfall and snowpack of the Blue Mountains.

Water Resource Issues The initial focus of ecoregion development within EPA was to use ecoregions as a

of the Columbia Plateau framework to classify streams and to assess water quality. The rationale behind the

Ecoregion useof terrestrial landscape characteristics to create water-quality regions was that

streams are a reflection of the watersheds from which they drain. In moist climatic

areas, information on drainage area size, stream discharge, and typical stream substrate is incorporated with the terrestrial landscape data layers to test consistency of

ecoregion boundaries with stream types. For the semiarid Columbia Plateau, however, objectives for water-quality assessment did not influence the boundary decisions

as much as they would in wetter areas. Traditional use of an ecoregion framework

for water-quality monitoring and assessment in moist environments carries with it

certain assumptions:

19
1. Perennial streams are used for sampling and setting biocriteria standards.

` 2. Many perennial streams within a region ensures a gradient in stream quality.

3. Reference streams are chosen that have their entire length within a particular

subregion and are considered representative of that subregion.

4.Small, wadeable streams are used for ease of sampling and to assure that their

drainage area lies entirely within a particular ecoregion or subregion.

These assumptions do not apply to a region as arid as the Columbia Plateau.

In the arid and semiarid areas of the Columbia Plateau, most summer precipitation

evaporates or is transpired, leaving little water for streamflow. In the driest parts of

the plateau, flow is zero or nearly zero. Almost the entire plateau, with the exception

of the mesic fringes (that is, “meadow steppe”; [Daubenmire 1970]), has an average

yearly runoff of less than 2.5 (1 in) centimeters per year. At Esquatzel Coulee, near

Connell, Washington, average yearly runoff is estimated at 0.25 centimeter (0.10 in)

per year. (Nelson 1991). Even in the Palouse Hills subregion, which has the highest

precipitation on the Plateau (40.6 to 58.4 centimeters [16 to 23 in]), of all the precipitation that falls, 84 percent is lost to evapotranspiration, 15 percent runs off as surface water, and 1 percent is left and assumed to percolate into the ground (Steiner

1987). Ephemeral streams flow only several days a year or fail to flow at all in particularly dry years. Perennial streams often originate in higher elevations where the

source includes snowmelt as well as rain. These “exotic” streams reflect mountain

conditions; they are not representative of the lower elevation subregions of the

Columbia Plateau through which they flow.

Streams have disappeared as a result of cultivation practices in steep loess hills.

Small stream channels may be plowed through and removed from the landscape.

Other channels simply fill with soil as it erodes off the hillsides. In the intensively

farmed areas, it is impossible to know the original substrate or riparian cover of

streams or how many streams once ran perennially. Some larger streams of the

arid plateau that do flow are totally appropriated during the irrigation season; water

is withdrawn until the streams are dry. Minimum flow regulations that have been

established to provide fish and wildlife habitat may be secondary to withdrawal rights

and thus are not implemented (Drost and others 1990). In other irrigated areas, the

reverse situation may occur; streams that would naturally not be perennial run with

irrigation return water.

If the Washington Department of Ecology and the Oregon Department of Environmental Quality are to use the ecoregion framework in the Columbia Plateau, as they

have elsewhere, to classify streams, monitor water quality, and eventually set

biocriteria standards, adjustments will have to be made to adapt bioassessment to

the arid conditions. The following are possible options:

1. Sample only larger systems.

2. Determine the role of springs in the monitoring program.

3. Use reference stream reaches as opposed to reference watersheds.

20
4. Choose reference reaches of streams within the Columbia Plateau but with

headwaters in neighboring mountainous ecoregions.

5. Model historic conditions.

6.Use reference sites from similar ecoregions.

Additional field work and interdisciplinary discussion are necessary to reexamine

water-quality monitoring and assessment in this arid region.

Literature Cited Allen, J.E.; Burns, M.; Sargent, S.C. 1986. Cataclysms on the Columbia: a

layman’s guide to the features produced by the catastrophic Bretz floods in the

Pacific Northwest. Portland, OR: Timber Press. 211 p.

Anderson, E.W. 1956. Some soil-plant relationships in eastern Oregon. Journal of

Range Management. 9(4): 171-175.

Baker, V.R.; Bjornstad, B.N.; Busacca, A.J. [and others]. 1991. Quaternary

geology of the Columbia Plateau. In: Morrison, R.B., ed. The geology of North

America. Vol K-2: Quaternary nonglacial geology: conterminous U.S. Boulder, CO:

The Geological Society of America: 215-250.

Bauer, H.H.; Vaccaro, J.J. 1990. Estimates of ground-water recharge to the

Columbia Plateau regional aquifer system, Washington, Oregon and Idaho for

predevelopment and current land-use conditions. Water Resour. Invest. Rep.

88-4108. Tacoma, WA: U.S. Department of the Interior, Geological Survey. 37 p.

(plus two map sheets).

Beieler, V.E. 1981. Soil survey of Douglas County, Washington. [Place of publication

unknown]: [Publisher unknown]. 180 p. In cooperation with: Washington State

University Agricultural Research Center.

Bretz, J.H. 1969. The Lake Missoula floods and the channeled scablands. Journal of

Geology. 77: 505-543.

Clarke, S.E.; White, D.; Schaedel, A.L. 1991. Oregon, USA, ecological regions and

subregions for water quality management. Environmental Management. 15(6):

847-856.

Daubenmire, R. 1956. Climate as a determinant of vegetation distribution in eastern

Washington and northern Idaho. Ecological Monographs. 26(2): 131-154.

Daubenmire, R. 1970. Steppe vegetation of Washington. Tech. Bull. 62. [Place of

publication unknown]: Washington Agricultural Experiment Station. 131 p.

Donaldson, N.C. 1980. Soil survey of Whitman County, Washington. [Place of

publication unknown]: [Publisher unknown]. 185 p. In cooperation with:

Washington State University Agricultural Research Center.

Drost, B.W.; Whiteman, K.J.; Gonthier, J.B. 1990. Geologic framework of the

Columbia Plateau aquifer system, Washington, Oregon and Idaho. Water Resour.

Invest. Rep. 87-4238. [Place of publication unknown]: U.S. Department of the

Interior, Geological Survey. 10 p. (plus 10 map sheets).

Franklin, J.F.; Dyrness, C.T. 1988. Natural vegetation of Oregon and Washington.

Corvallis, OR: Oregon State University Press. 452 p.

21
Hooper, P.R.; Reidel, S.P. 1989. Dikes and vents feeding the Columbia River

basalts. In: Joseph, N.L. [and others], eds. Geologic guidebook for Washington

and adjacent areas. Info. Circ. 86. Olympia, WA: Washington Division of Geology

and Earth Resources. 369 p.

Johnson, D.R.; Makinson, A.J. 1988. Soil survey of Umatilla County area, Oregon.

[Place of publication unknown]: [Publisher unknown]. 388 p. In cooperation with:

U.S. Department of the Interior, Bureau of Indian Affairs; Oregon Agricultural

Experiment Station.

Nelson, L.M. 1991. Surface-water resources of the Columbia Plateau in parts of

Washington, Oregon and Idaho. Water Resour. Invest. Rep. 88-4105. [Place of

publication unknown]: U.S. Department of the Interior, Geological Survey. (4 map

sheets with text).

Raisz, Erwin. 1941. Landforms of the northwestern states, rev. 1965. [Place of

publication unknown]: [Publisher unknown]. (Map scale approximately 1 inch =

20 miles).

Rasmussen, J. 1971. Soil survey of Benton County area, Washington. [Place of

publication unknown]: [Publisher unknown]. 72 p. In cooperation with: Washington

Agricultural Experiment Station.

Reidel, S.P.; Campbell, N.P. 1989. Structure of the Yakima Fold Belt, central

Washington. In: Joseph, N.L. [and others]. Geologic guidebook for Washington

and adjacent areas. Info. Circ. 86. Olympia, WA: Washington Division of Geology

and Earth Resources. 369 p.

Steiner, F. 1987. The productive and erosive Palouse environment. Coop. Exten.

Bull. Pullman, WA: Washington State University. 42 p.

Stockman, D. 1981. Soil survey of Lincoln County, Washington. [Place of publication

unknown]: [Publisher unknown]. 167 p. In cooperation with: Washington State

University Agricultural Research Center.

Stoffel, K.L.; Joseph, N.L.; Waggoner, S.Z. [and others]. 1991. Geologic map of

Washington-northeast quadrant. GM-39. [Place of publication unknown]:

Washington Division of Geology and Earth Resources. 1:250,000; (and text 36 p.).

U.S. Department of Agriculture, Soil Conservation Service. 1986. Major land

resource areas. 1:3,500,000; (Map of Oregon).

U.S. Department of the Interior, Geological Survey. 1982. The channeled

scablands of eastern Washington: the geologic story of the Spokane flood.

GPO 359-019. Washington, DC: U.S. Government Printing Office. 24 p.

Walker, G.W.; MacLeod, N.S. 1991. Geologic map of Oregon. Denver, CO: U.S.

Department of the Interior, Geological Survey. 1:500,000; (two sheets).

22
Section 2—Level IV Ecoregions of the Blue

Mountains Ecoregion of Oregon,

Washington, and idaho

by Sandra A. Bryce and James M. Omernik

The Blue Mountains of north-central Oregon form a transverse bridge between the

northern Rocky Mountains of western Idaho and the Oregon Cascade Range. The

overall structure of the Blue Mountains is a large anticline with a steep north flank in

southeastern Washington State, high elevations in the midsection, and gentle south

slopes that join the high lava plains of central Oregon (McKee 1972). The wide arc

of mountains encompasses three different geologies—a continuation of the Columbia

Plateau basalts in the north; a collection of “accreted terranes” (that is, ocean crust

and volcanic islands that collided with the western end of the continent) in the central

part; and more recent rhyolites, andesites, and basalts along the southern perimeter.

Individual ranges include the Ochoco, Aldrich, Strawberry, Greenhorn, Elkhorn,

Wallowa, and Seven Devils Mountains. Elevations range from less than 275 meters

(900 ft) in the canyon depths to nearly 3050 meters (10,000 ft) for the Matterhorn and

Sacajawea, the highest peaks in the Wallowa Mountains.

The ecoregion map presented here (insert B) and the report that accompanies it

organize the complexity of this region. The explanations below take the reader first

through the component landscape characteristics. Then we rearrange and integrate

this information in the individual regional descriptions to illustrate the rationale for the

boundary decisions. The available information for any region is not evenly distributed.

The Blue Mountains area is of great interest to geologists; the available literature is

heavily weighted in geology. We hope, however, that the descriptions will illuminate

the distinctions among the regions and serve as a reference to those who may use

the ecoregion map for any of the applications discussed in the introductory chapter

or others not yet invented.

Climate Water became a limiting factor to ecosystems in the Blue Mountains with the rise of

the Cascade Range 20 to 30 million years ago, which formed a barrier to the eastward flow of weather systems off the Pacific Ocean. As a result, the semitropical

climate of the area became temperate and continental (Alt and Hyndman 1978). Precipitation is light, with most of it occurring in winter; thunderstorms do build occasionally over the higher ranges during the hot, dry summer. In winter, the continental

temperature extremes are somewhat reduced because the region is protected from

the full brunt of arctic air flow by the northern Rocky Mountains. In summer, there is

enough marine influence over the northern and central Blue Mountains to moderate

extremes in heat and drought.

The degree of continentality differs across the Blue Mountains from west to east as

well as latitudinally. The Cascade rain shadow extends 233 kilometers (140 mi) to

the east to the base of the Elkhorn range. In the rain shadow, light precipitation, high

evapotranspiration, and wide temperature fluctuations result in wide expanses of dry

forest dominated by ponderosa pine. The xeric conditions and temperature extremes

are even greater in the south-central Blue Mountains and along the southeastern

foothills where the marine influence is entirely blocked.

23
The continental climate in the northeastern Blue Mountains is masked by a swath of

marine air that penetrates eastern Oregon and Washington from the Pacific Ocean.

Weather systems flowing through the Columbia River Gorge, penetrating the Cascade

Range, bring precipitation to the northern Blue Mountains slopes three seasons of the

year. Here, increased cloudiness, higher humidity, and precipitation foster a productive mesic forest. This wetter, maritime-influenced section is bounded by the WallowaSeven Devils Mountains to the east and the Elkhorn range to the south.

The planes of influence delimiting ecosystems in the Blue Mountains are elevational

as well as latitudinal. In general, as moisture increases and temperature decreases

with elevation, forest productivity improves until heavy snowpack and severe winters

shorten growing seasons and limit tree growth at elevations above 1830 meters

(6,000 ft).

The capabilities of these ecoregions for particular land uses also are determined by

moisture availability, growing season, and temperature. Grazing, mining, logging,

farming, road building, and irrigation have been practiced in the Blue Mountains for

150 years. Many other authors have traced the history of land use and management

practices that have contributed to the present-day condition of the Blue Mountains

ecosystems (Harvey and others 1994, Hessburg and others 1994, Irwin and others

1994, Johnson 1994, Johnson and others 1994, Lehmkuhl and others 1994, Mclntosh

and others 1994, Oliver and others 1994, Bobbins and Wolf 1994, Skovlin 1991).

Major land uses and their effects on particular landscape types are discussed in the

descriptions of the individual ecoregions.

Geology—The Birth of In Devonian to early Jurassic time (275 to 200 million years ago), the Blue Mountains

the Blues began as a group of offshore islands in the eastern Pacific Ocean. They had formed

as island arcs behind subduction zones in the ocean floor. At a subduction zone, an

oceanic plate (a piece of Earth’s crust) slides beneath another plate (oceanic or

continental). Intense heat and pressure melt the rocks on the sea floor into magma,

which then resurfaces as volcanic eruptions, forming a continental mountain range or

a line of volcanic islands. Thick ocean sediments and even an occasional piece of

ocean crust may be scraped off and piled against the side of the subduction trench.

At about the same time (geologically speaking), 200 million years ago, the North

American Continent separated from Europe, carried westward by the widening rift in

the floor of the Atlantic Ocean. Oregon’s land mass did not exist; the Pacific shore

of the continent was then in western Idaho. As the North American Continent moved

slowly, but inexorably westward, it engulfed a group of offshore islands about 100

million years ago (White and others 1992). Two island groups have been mapped

in the Blue Mountains: the Wallowa-Seven Devils terrane and the Olds Ferry terrane

near Huntington, Oregon. Remains of limestone coral reefs in the Wallowa Mountains

indicate that the islands formed under subtropical conditions in a warm shallow sea

(Fifarek and others 1994). The offshore sediments and the erosional material from the

islands (shales and fine sandstones) settled between the islands and the mainland

as well as between the islands and the subduction trench. These sediments are evident in the Aldrich Mountains (the Izee terrane) and in the Wallowa Mountains (White

and others 1992). The island arcs may be remnants of a more extensive system; their

rocks are chemically similar to those in arcs accreted to western Canada as well as

24
the Aleutian Islands (Brooks 1979, White and Vallier 1994). Here in the Blue Mounains, the accreted land meets the ancient rocks of the North American plate at the

“suture zone,” a north-south trench along the western Idaho border, extending from

Cascade Reservoir north to Riggins, Idaho (Hooper and Swanson 1990).

The chaotic result of subduction zone geology is represented by the Baker and Grindstone terranes, the formations that form the core of the central Blue Mountains. They

are a patchwork of ocean sediments, sandstone, and argillite (shaley mudstone), and

deep seacrust rocks such as pillow lavas, serpentinite, and gabbro, that escaped

Earth’s molten maw. Mixed in with these formations are the metasedimentary and

metavolcanic rocks metamorphosed in the superheated contact zones near the subduction trench (Brooks 1979, Walker and Robinson 1990, White and others 1992).

The complex of sediments, lavas, and ocean crust making up the accreted terranes

is aptly called a melange. Melange Formations worldwide signal the presence of subduction zones and newly accreted land.

The process of accretion also created reservoirs of magma that recrystallized underground 100 to 130 million years ago to form the granitic core of the Wallowa Mountains, the northern Elkhorn Mountains, and other scattered peaks. The metamorphic

areas surrounding these intrusions are the source of gold and other metal deposits

that attracted early settlers to the Blue Mountains (Goldstrand 1994, Thayer 1990).

This addition of new land occurred during pre-Cenozoic time. Then about 60 million

years ago, during the Tertiary period of the Cenozoic era, intense volcanic activity

changed the character of the region yet again. Over a period of 40 million years, the

accreted terranes were buried by volcanic material from the chain of volcanoes of the

Clarno period, the immense ash falls of the John Day Formation, the Strawberry

Mountains volcanics, and the Columbia River and Picture Gorge flood basalts.

Erosion has since exposed the older pre-Cenozoic rock at higher elevations (Orr

and others 1992, Thayer 1990).

The Clarno Formation is the remnant of a range of volcanoes, formed during the

Eocene period 55 to 35 million years ago, that followed the northeast-southwest axis

of the Blue Mountains. The rocks are mostly andesitic, but they include some basaltic

and rhyolitic rocks. The volcanic cones mostly have eroded away; scattered remnants

may be seen as conical plugs (for example, White Butte and Black Butte in Wheeler

County, Oregon) (Walker and Robinson 1990).

By the time of the John Day ash falls, about 35 million years ago, the sea-floor subduction zone had changed to a north-south line rather than the northeast trending

Wallowa-Klamath Mountains line (Walker and Robinson 1990). The new location set

the stage for the formation of the Cascade Range that would eventually block the

marine air flow from the interior and change the warm, moist climate of Clarno times

to the continental climate of today (Alt and Hyndman 1978).

Between about 17.5 and 6 million years ago, incredible floods of fluid basalt filled

what was once an inland sea in central Oregon and Washington. This Columbia

River Basalt Group constitutes the entire Columbia Plateau and the northern third of

the Blue Mountains. Most of the flows (90 percent) issued from long fissure vents

and dike swarms in the northeastern Blue Mountains, except for the Picture Gorge

basalt that erupted from vents in the John Day River basin in the central Blue Mountains (Hooper and Swanson 1990).

25
The northwestward tilting of the Blue Mountains continued throughout this period,

partly due to the rise of the subterranean granitic bodies (the Idaho batholith to the

east and the smaller granitic bodies under the Wallowas, Elkhorns, and the Nez

Perce Plateau) and partly because of regional stresses, faulting, and compression.

Faulting defined the major valleys (Grande Ronde, Baker, and Wallowa), and uplifted

the adjacent mountain ranges (Wallowas, Elkhorns, and Strawberrys). Since these

dramatic geologic happenings, eons of erosion and Pleistocene glaciation have

sculpted the peaks and filled the basins with sediments, producing the familiar,

seemingly stable, landscape of today.

Blue Mountains Soils1 The geologic mayhem in the parent material has produced a variety of soil types

across the Blue Mountains. There are, however, zones of moisture, temperature,

elevation, and aspect that create a discernible pattern of general soil types across

the landscape.

In this moisture-limited region, much of the lower elevation soils are xeric or aridic;

that is, they are dry for at least 60 to 90 days in summer. Early moisture stress effectively shortens the active growing season. In addition, much of the lower elevation,

drier soil is derived directly from the geologic parent material. This condition effectively increases the droughtiness of the soil because it is more likely to have rock

fragments throughout that reduce the amount of soil available for rooting as well as

the water-storage capability (Andersen 1956). The coarse fragments make soil derived from basalt and andesite slightly less erodible than fine-textured soil. In xeric soil

regimes, the lack of water limits the development of soil organic content and slows

soil weathering. Productivity in xeric areas is dependent on a thin surficial organic

layer or on regular fires to release nutrients accumulated in woody debris and dried

grasses (Harvey and others 1994). Thus, when moisture is limiting, several factors

contribute to a less productive medium for plant growth.

The geologic parent material for soils are the rhyolites and tuffs in the southern Blue

Mountains, mixed volcanic debris and ash in the John Day-Clarno region, sedimentary material in the Aldrich and Elkhorn Mountains, and andesite and basalts in the

Strawberry Mountains. Mixed with these are the droughty soils of the granitic and

metamorphic inclusions. Xeric conditions and characteristic plant cover persist into

higher elevations on south-facing slopes and on metamorphic parent material.

At higher elevations, above about 762 meters (2,500 ft) in the north and 1525 meters

(5,000 ft) in the south, conditions become cooler and moister and also more productive. Soil at these elevations is normally udic or moist. In the udic moisture regime,

there are fewer than 45 days of dryness in the 120 days following June 20. The

temperature regime is either frigid or, in the higher elevations above 1525 meters

(5,000 ft), cryic.

1 Thorsen, T.; Lammers, D. 1994. Bailey subsection

descriptions for Blue Mountains soils. Draft dated 1994 to

Sandra Bryce. On file with: Natural Resources Conservation

Service, Portland OR.

26
The most productive soils of the Blue Mountains are those composed of fine materials

that have been aerially deposited. Ash deposits from the eruptions of Glacier Peak

and Mount Mazama (12,000 and 6,600 years ago, respectively) are as much as

1 meter (39 in) thick in the mid- to high-elevation forested areas. Much of the ash has

eroded away in the lower elevation grasslands and on south-facing slopes, but it has

been preserved in more mesic zones, such as north slopes and sites having had a

continuous forest cover. The fine silt loam ash soils have a high water-holding capacity, a high water-infiltration rate, and a largely rock-free growing medium. Again, most

of the nutrients are near the surface. Without a vegetative cover, ash soils are vulnerable to erosion and subsequent loss of productivity (Harvey and others 1994). In

general, the major areas of ashy soil correspond with the regions of mesic forest

(insert B 111), especially in the central and northern Blue Mountains.

Aeolian loess (glacial silt deposited by wind during the Pleistocene) is also a significant addition to Blue Mountains soils, particularly in the northern Blue Mountains

adjacent to the Columbia Plateau (see section 1, above). Like ash, loess deposits

can ameliorate the droughtiness of the soil. Loess soils also are fine-textured, rock

free, and high in nutrients.

Blue Mountains As we walk the landscape and view the patterns of vegetation at that scale, we

Vegetation notice the variability in plant associations, responding to variations in disturbance,

microclimate, aspect, and local topography. Various species dominate over time as

conditions change. How can we generalize about such diversity?

We can compare this conundrum with the phenomenon that happens on inspection

of a pointillist painting, for example, the Isle du Gran Jatte by Seurat. From the vantage point of a few inches away from the canvas, we see only a dizzying array of

many-colored dots. But if we step back away from the painting, the dots fuse to

reveal pattern. Similarly, if we conceptually back away far enough from the landscape, the confusing collection of plant associations in the Blue Mountains disclose a

pattern, dependent on temperature, elevation, growing season, soil type, and depth

(table 2).

The most apparent pattern in the area is a progression of vegetation types with increasing elevation, beginning with grasslands at the lowest elevations and changing

to shrublands, ponderosa pine woodlands, true fir mesic forest, subalpine forest and

parkland, and alpine meadows as elevation increases. Tying these patterns to a map

is a more difficult prospect. Guided by elevation, parent material, soil type, fire regime,

and historic vegetation patterns, however, we have created a model that includes

vegetation as one element in the integration of landscape characteristics that compose a map of ecosystems.

In the lowest elevations, grassland communities prevail in the areas of xeric and

aridic soils. They range from bluebunch wheatgrass-Sandberg’s bluegrass associations in the warmest, driest canyons to Idaho fescue associations in deeper, moister

soils. Shrublands and juniper-grassland savannah form the transition from grassland

to forested slopes. Along the southern foothills, bitterbrush, mountain-mahogany, and

sagebrush mix with juniper to provide cover, browse, and berries for birds, elk, and

deer (Johnson and Clausnitzer 1992). In the north-central and northern Blue Mountains, sagebrush and western juniper are replaced by a mesic shrub assemblage—

ninebark, common snowberry, serviceberry, Rocky Mountain maple, and ocean-spray.

Text continues on page 33.

27
Table 2—Native vegetation of the Blue Mountains subregionsa

Subregion Genus species Common name

Subregions in the Cascade

rain shadow :

John Day/Clarno Uplands (11a) Juniperus occidentalis Hook. Western juniper

Artemisia tridentata Big sagebrush

Purshia tridentata Bitterbrush

Agropyron spicatum Bluebunch wheatgrass

Festuca Idahoensis

Poa sandbergii Vasey

John Day/Clarno Highlands (11b) Pinus ponderosa Ponderosa pine

Pinus contorta Dougl. ex Loud. Lodgepole pine

Pseudotsuga menziesii (Mirb.) Franco Douglas-fir

Purshia tridentata Bitterbrush

Cercocarpus ledifolius Nutt. Mountain-mahogany

Agropyron spicatum Bluebunch wheatgrass

Calamagrostis rubescens Buckl. Pinegrass

Carex geyeri Boott Elk sedge

Maritime-Influenced Zone (11c) :

Mesic Forest Zone (11l) Abies grandis Dougl. Forbes Grand fir

Pseudotsuga menziesii Douglas-fir

Pinus contorta Lodgepole pine

Picea engelmannii Parry ex Engelm. Engelmann spruce

Larix occidentalis Nutt. Western larch

Abies lasiocarpa (Hook.) Nutt Subalpine fir

Linnaea borealis L. Twinflower

Spirea betulifolia Pall. Birchleaf spirea

Acer glabrum Torr. Rocky Mountain maple

Taxus brevifolia Nutt. Pacific yew

Vaccinium membranaceum Dougl. Big huckleberry

Vaccinium scoparium Leiberg Grouse huckleberry

Subalpine Zone (11m) Abies lasiocarpa Subalpine fir

Pinus contorta Lodgepole pine

Larix occidentalis Western larch

Picea engelmanii Engelmann spruce

Pinus albicaulis Engelm. Whitebark pine

28
Table 2—Native vegetation of the Blue Mountains subregionsa

Subregion Genus species Common name

Melange subregion (11d) : Pinus ponderosa Ponderosa pine

Juniperus occidentalis Western juniper

Pseudotsuga menziesii Douglas-fir

Cercocarpus ledifolius Mountain-mahogany

Purshia tridentata Bitterbrush

Ribes cereum Dougl. Squaw currant

Symphoricarpos spp. Snowberry

Calamagrostis rubescens Pinegrass

Carex geyeri Elk sedge

Mesic Forest Zone (11l) Abies grandis Grand fir

Pseudotsuga menziesii Douglas-fir

Pinus contorta Lodgepole pine

Picea engelmannii Engelmann spruce

Larix occidentalis Western larch

Abies lasiocarpa Subalpine fir

Linnaea borealis Twinflower

Spirea betulfolia Birchleaf spirea

Acer glabrum Rocky Mountian maple

Taxus breviifolia Pacific yew

Vaccinium membranaceum Big huckleberry

Vaccinium scoparium Grouse huckleberry

Subalpine Zone (11m) Abies lasiocarpa Subalpine fir

Pinus contorta Lodgepole pine

Picea engelmannii Engelmann spruce

Pinus albicaulis Whitebark pine

Artemisia tridentata Alpine sagebrush

Festuca idahoensis Idaho fescue

Festuca viridula Vasey Green fescue

Carex geyeri Elk sedge

Carex hoodii Boott Hood’s sedge

Wallowas/Seven Devils subregio (11e): Pinus ponderosa Ponderosa pine

Pseudotsuga menziesii Douglas-fir

Physocarpus malvaceus (Greene) Kuntze Mallow ninebark

Symphoricarpos albus Common snowberry

Acer glabrum Rocky Mountain maple

Amelanchier ainifolia Nutt. Western serviceberry

Purshia tridentata Bitterbrush

Artemisia tridentata vaseyana Nutt. Mountain big sagebrush

29
Table 2—Native vegetation of the Blue Mountains subregionsa (continued)

Subregion Genus species Common name

Mesic Forest Zone (11l) Abies grandis Grand fir

Abies lasiocarpa Subalpine fir

Clintonia uniflora (Schult.) Queen’s cup beadlily

Vaccinium membranaceum Big huckleberry

Subalpine Zone (11m) Abies lasiocarpa Subalpine fir

Picea engelmannii Engelmann spruce

Tsuga mertensiana (Bong.) Carr. Mountain hemlock

Festuca viridula Green fescue

Carex hoodii Hood’s sedge

Canyons and Dissected Highlands (11f) Pinus ponderosa Ponderosa pine

Pseudotsuga menziesii Douglas-fir

Larix occidentalis Western larch

Abies grandis Grand fir

Snake and Salmon River Canyons (11g) Pinus ponderosa Ponderosa pine

Purshia tridentata Bitterbrush

Rosa Rose

Symphoricarpos albus Common snowberery

Glossopetalon nevadense Gray. Spiny greenbush

Agropyron spicatum Bluebunch wheatgrass

Poa sandbergii Sandberg’s bluegrass

Festuca idahoensis Idaho fescue

Continental Zone Highlands (11h) Pinus ponderosa Ponderosa pine

Pseudotsuga menziesii Douglas-fir

Artemisia tridentata Big sagebrush

Cercocarpus ledifolius Mountain-mahogany

Purshia tridentata Bitterbrush

Ribes cereum Squaw currant

Calamagrostis rubescens Pinegrass

Carex geyerii Elk sedge

Continental Zone Foothills (11i) Juniperus occidentalis Western juniper

Artemisia rigida Rigid sagebrush

Artemisia arbuscula Nutt. Low sagebrush

Cercocarpus ledifolius Mountain-mahogany

Purshia tridentata Bitterbrush

Artemisia tridentata Mountain big sagebrush

Festuca idahoensis Idaho fescue

Agropyron spicatum Bluebunch wheatgrass

30
Table 2—Native vegetation of the Blue Mountains subregionsa (continued)

Subregion Genus species Common name

Batholith Contact Zone (11j): Pinus ponderosa Ponderosa pine

Pseudotsuga menziesii Douglas-fir

Physocarpus malvaceus Mallow nine-bark

Calamagrostis rubescens Pinegrass

Mesic Forest Zone (11l) Pinus ponderosa Ponderosa pine

Larix occidentalis Western larch

Pinus contorta Lodgepole pine

Picea engelmannii Engelmann spruce

Blue Mountains Basins (11k) Symphoricarpus albus Common snowberry

Sarcobatus spp. Greasewood

Festuca idahoensis Idaho fescue

Poa sandbergii Sandberg’s bluegrass

Deschampsia caespitosa (L.) Beauv. Tufted hairgrass

Agrostis diegoensis Vasey Redtop bentgrass

Carex spp. Sedges

a By legend number in insert B.

31
Ponderosa pine grows in a wide range across much of the Blue Mountains as a

climax species in the warmest and driest forested areas and as a serai dominant in

areas of frequent fire (Harvey and others 1994, Hessburg and others 1994). As a

serai dominant, it grows at the moister end of the xeric soil regime where grand fir is

technically the climax species. Here, however, the grand fir is at the extreme end of

its range. It is susceptible to fire, moisture stressed, and prone to disease and insect

infestations (Hessburg and others 1994, Johnson and others 1994). Under a normal

fire regime, with a fire frequency as short as 10 years, the ponderosa pine persists,

whereas the grand fir seedlings continually succumb to fire except near springs or

other moist refugia.

Historically, the forest types were rather sharply bounded by elevation. Ponderosa

pine dominated the xeric soil regions, the fire-prone areas, whereas true fir associations, the mesic forest, dominated higher elevations. The mesic forest zone historically began at about 762 meters (2,500 ft) in the north and 1500 meters (4,900 ft) in

the southern mountains.

Before widespread fire suppression, these mesic forests had a low fire frequency

of 50 to 300 years or more; but the fires were hot, intense, and extensive. Lodgepole pine and western larch, the serai species at the higher elevations of 1220 to

2285 meters (4,000 to 7,500 ft), revegetated the burns to create a patchy forest landscape. Insect and disease infestations cycled within the limited area of susceptible

true fir forest, but infestations did not often reach epidemic proportions (Hessburg and

others 1994).

Fire suppression has blurred the historical-elevational zonation of forest vegetation.

Present-day vegetation patterns do not give us a clear picture of the natural affinities

of forest plant associations. Because of 60 years of fire suppression, Douglas-fir,

grand fir, and Engelmann spruce have expanded their range to lower elevations

beyond their normal mesic locations. During this same period, old-growth stands of

ponderosa pine and western larch have been cut, leaving thickets of late-successional

fir forest. With the increase in acreage of overstocked mesic forest, insects and

disease have become more common. Over the years, the proportion of forest land

in the Blue Mountains dominated by ponderosa pine has declined on all ownerships

from 80 percent in 1936 to 25 percent in 1992 (Hessburg and others 1994).

In the new atmosphere of ecosystem management, proposed management strategies

include uneven-age management of multiple tree species, reduction of grazing densities, restoration of understory shrub communities (Irwin and others 1994), and prescribed burning to emulate the historic fire regimes and to reestablish the serai forest

(Oliver and others 1994). A map like the ecoregion map presented here (insert B),

developed as a model of a time when there were minimal human impacts on the

landscape, can serve to guide restoration efforts by suggesting a more “natural” distribution of vegetation. With that goal in mind, the ecoregions delineated here reflect the

time when ponderosa pine in parklike stands dominated both the lower elevation sites

and the xeric grand fir and Douglas-fir series sites as well.

32
There is some discussion about exactly how much of the presettlement vegetation

pattern was due to Native American “prescribed burning” (Robbins and Wolf 1994).

Could the parklike stands of ponderosa pine have been “managed” by early Native

Americans? Perhaps early man and the forest community have coevolved since the

Pleistocene. Evidence indicates that the forest has evolved under a fire regime,

whether human-caused or not, and that it maintained itself in a healthier condition

then than today (Harvey and others 1994, Hessburg and others 1994, Johnson 1994,

Lehmkuhl and others 1994, Robbins and Wolf 1994).

The historic view of an area may provide guidance to restoration efforts by serving as

a model or ideal goal. Though we may never reach the ultimate goal (the presettlement condition), what is attainable will be somewhere between the degraded condition and the historic condition. How closely we approach the goal depends on social

values and the availability of funding.

In summary, the climate, geology, soil, historic and present-day vegetation, and important influences on these factors (for example, the fire regime) were the major

 categories of information that contributed to the regional delineations for this project.

Map analysis, consultation with regional experts in meetings and over the phone, and

a literature review were all integrated to create the map of Level IV ecoregions of the

Blue Mountains ecoregion of Oregon and Washington. The following regional descriptions indicate the rationale behind specific boundary decisions.

Descriptions of the Blue Composite subregions—To limit the number of subregions and to strive for carloMountains Subregions graphic simplicity, several disjunct subregions that are the result of elevational factors

have been combined into two composite subregions, the Mesic Forest (insert A, 11l)

and the Subalpine Zones (insert A, 11m). Thus, there is just one subalpine subregion

instead of three (Wallowas subalpine, Elkhorns subalpine, and Strawberry Mountains

subalpine); they are graphically displayed as disjunct areas of the same color. The

scattered portions of each composite subregion have a general similarity across the

Blue Mountains ecoregion. There is, however, some latitudinal variability among the

disjunct areas. The Mesic Forest and Subalpine Zones ecoregions are described in

general below, and each individual area (for example, Wallowas subalpine) is then

described in more detail in its appropriate subregional description.

Subalpine Zone—The widest expanses of the Subalpine Zone (insert A, 11m;

insert B, 11m) appear in the high Wallowa, Elkhorn, Greenhorn, and Strawberry

Mountains. Elevations at which the subalpine forest becomes broken by high meadows and parkland differ from north to south. Subalpine parkland, that is, the mosaic of

forest patches and meadows, begins at about 1830 meters (6,000 ft) in the northern

Blue Mountains and at 2130 meters (7,000 ft) in the south-central Blue Mountains.

The high-elevation forests and meadows share a cold climate, cold, often shallow,

soils, short growing season (10 to 70 days), heavy snowpack, and high annual precipitation (85 to 150 cm).

The subalpine lithology differs from Columbia River basalt in the northern Blue Mountains to granitics in the Wallowas, granodiorites in the Elkhorns and Greenhorns, and

ultramafics and andesites in the Strawberry Mountains. Subalpine fir, and its serai

partners, lodgepole pine, western larch, and Engelmann spruce, reach their highest

potential on silt loam soils derived from volcanic ash and loamy sands from pumice

33
and ash. Lodgepole pine prefers ashy soil on gentle ridges with slopes less than

15 percent. Western larch can grow in steeper areas, where deep colluvial soils provide stored moisture (Johnson and Simon 1987). In more extreme locations to 2440

meters (8,000 ft), whitebark pine, also serai to subalpine fir at lower elevations,

becomes codominant.

Mesic Forest Zone—The Mesic Forest Zone (insert A, 111; insert B, 111) appears

throughout the Blue Mountains in areas of low-moisture stress. The largest expanses

are in the north where marine air flowing through the Columbia River Gorge brings

high rainfall amounts. Elsewhere, in the central and southern Blue Mountains, elevation increasingly influences the distribution of mesic forest. As the climate becomes

more continental, only higher elevations capture the amount of precipitation necessary

to support the mixed-conifer and fir forests. Mesic forests have a high affinity for ashderived soils with high moisture-holding capacity, which retard the onset of summer

drought in mountainous areas with cooler temperatures. The mesic forest starts at

about 915 meters (3,000 ft) in the north; farther south and west, the true fir forest is

limited to areas above 1830 meters (6,000 ft) or to northern aspects.

The subregion map (insert B) depicts the Mesic Forest Zone as it might be under a

more “natural” fire regime. The early map by Andrews and Cowlin (1936) for the forest types of the U.S. Department of Agriculture’s Forest Service served as a model

for the delineations of mesic and xeric forest on the subregion map. This 1936 map

provides a snapshot of forest distributions before fire suppression and widespread

high-grade logging had changed the sharp elevational patterns of the east-side forest. As a result, the mesic forest delineated on the subregion map (insert B) is an expression of the higher, moister end of the grand fir series. Areas where grand fir is

technically the climax species, but where it would not normally reach maturity because of frequent fires, appear as xeric forest on the subregion map. Thus, the

mapped zones of xeric and mesic forest do not match the full range of the true fir

forest associations, but they do correspond more closely to the xeric and udic soiltemperature regimes.

Subregions in the Cascade rain shadow—As the Cascade Range began to block

the flow of moist Pacific air to what is now central Oregon 20 to 30 million years ago,

the warm, tropical climate of the Eocene epoch gave way to a drier, cooler, continental climate. The areas identified on the map as the John Day-Clarno Uplands

(insert B, 11 a) and the John Day-Clarno Highlands (insert B, 11b) constitute two

elevational divisions of subregions in the Cascade rain shadow.

John Day-Clarno Uplands—The John Day-Clarno Uplands (insert A, 11 a; insert B,

11 a) subregion takes its name from two geologic formations that appear in several

subregions of the Blue Mountains; however, their greatest extent and most distinctive expression occur within the boundaries of this subregion. The John Day-Clarno

Uplands are a ring of dry foothills that surrounds the western perimeter of the Blue

Mountains and separates the north-central Blue Mountains from the southern Blue

and Ochoco Mountains. The “John Day Country” is a rough sea of highly dissected

hills, palisades, and colorful ash beds dotted with junipers and cut by the valleys of

the John Day and Crooked Rivers. Elevations range from 457 to 1525 meters (1,500

to 5,000 ft). Precipitation falls as spring and fall rains and light snow in the winter.

Annual precipitation differs with elevation, from 23 centimeters (9 in) at lower elevations to 40 centimeters (16 in) at higher elevations.

34
The Clarno Formation of 54 to 37 million years ago (Eocene and lower Oligocene

periods) began as a pre-Cascade Range chain of andesitic volcanic cones erupting

along the northeast trending axis of the Blue Mountains. The location of the Clarno

volcanoes indicates the past presence of a parallel subduction zone offshore (Walker

and Robinson 1990). The Clarno Formation today comprises various eroded remnants of the mountain chain: andesites, basalts, tuffs, breccias, and colorful cliffs

of petrified mudflow (lahars). Red paleosols (fossil forest soils) and fossilized leaves

and nuts give evidence of the tropical climate of the time (Retallack 1991).

By the time of the John Day Formation, 37 to 22 million years ago (Oligocene to

early Miocene periods), the ocean floor subduction zone had shifted to the west and

taken up a north-south position west of the rising Cascade Range. Several thousand

feet of airborne and waterborne tuffs and ash filled a topographic basin between the

west side of the Cascade Range and the now-extinct Clarno volcanic chain. The ash

flows and airfall tuffs are assumed to have come from several sources east of the

Cascade Range (Robinson and others 1990, Thayer 1990). Robinson and others

(1990) give us a startling realization of the immensity of geologic time by relating that

the lower unit of the three strata of John Day ash (350 meters [1,148 ft] deep) spans

a period of 12 million years of deposition at a rate of about 28 millimeters (1.1 in) per

1,000 years. These formations of red, green, and grey ash are softer and more easily

eroded than the surrounding basalt and, thus, form valleys or bowllike depressions.

The ashy beds weather to a fine clay. The fossilized remains of a diverse mammalian

fauna have been preserved in the John Day Fossil Beds National Monument near

Picture Gorge, Oregon (Thayer 1990).

Outside of the John Day ash beds, the soils are more varied, reflecting the various

volcanic parent materials in the region. The soils are generally deep to bedrock with

a stony loam surface layer and a clay loam or clay subsoil. The soils at lower elevations have an aridic soil moisture regime with average annual precipitation amounts

of less than 30 centimeters (12 in). They include Aridic Palexerolls, Chromic

Haploxererts, Xeric Paleargids, Aridic Haploxerolls, and Aridic and Lithic Argixerolls.

The soils at higher elevations have a xeric moisture regime with annual precipitation

amounts of 35 centimeters (about 14 in). These soils include Lithic Argixerolls, Calcic

Pachic Argixerolls, and Pachic Palexerolls. Soils derived directly from basalt differ in

that they are shallow to moderately deep, with a surface layer of very cobbly loam

and a very cobbly clay-loam subsoil. Basaltic soils include Lithic Argixerolls and

Aridic Argixerolls.

The potential natural vegetation of the John Day-Clarno region consists of grassland

and grassland savannah. Bluebunch wheatgrass, Idaho fescue, and Sandberg’s

bluegrass with big sagebrush and bitterbrush cover the lower elevation, drier areas.

Juniper woodland forms the transition zone between the dry grasslands and the

ponderosa pine forests of the higher elevations. The juniper zone ranges in elevation

from 760 to 1400 meters (2,483 to 4,593 ft) where the rainfall is between 20 and 30

centimeters (8 to 12 in).

35
Juniper woodland and savannah have increased markedly over the last 50 years.

The expansion can be traced through the photographic record. The change in spatial

extent is also apparent when comparing a forest type map of the 1930s with a

present-day vegetation map (Andrews and Cowlin 1936, Kagan and Caicco 1992).

Though it is theorized that a combination of fire suppression and cattle grazing

caused the most recent advance in juniper distribution, the fossil record shows regular expansion and contraction of juniper distribution over the last 5,000 years.

Increased moisture and fewer, low-intensity fires favored juniper, whereas drought

and increased fire suppressed it (Johnson and others 1994). Juniper has an affinity

for the clay soils of the region; it benefits from the relatively high moisture-retaining

capacity of clays (Johnson and Simon 1987).

The southern edge of the Columbia River basalt marks the northern boundary of

the John Day-Clarno Uplands (insert B, 11 a). The boundary is quite clear near

Antelope, Oregon, where the basalt flows of the plateau crop out in a prominent

rim called the Antelope Scarp. Farther east, on Highway 19 between Fossil, Oregon,

and Mayville, Oregon, one can drive 11.3 kilometers (7 mi) up a steep grade to the

level of the Columbia Plateau. The change from John Day country to the rolling

Columbia Plateau is sharp enough here to be a “line drawn on the ground.” The

south-western boundaries of the John Day-Clarno subregion end on the juniper flats

of the Deschutes River basin. The transition from the John Day-Clarno Uplands

(insert B, 11 a) to the Continental Zone Foothills (insert B, 111) subregion is a

combination of a change in geology and climate. In the Continental Zone Foothills

(insert B, 11i), the regional aspect is more southerly, the climate more continental,

and the underlying geology changes from John Day and Clarno deposits to more

recent volcanics and tuffs.

John Day-Clarno Highlands—The change from juniper and grassland savannah to

ponderosa pine woodland marks the boundary between the John Day-Clarno Uplands

(insert B, 11 a) and the forested John Day Clarno Highlands (insert A, lib; insert B,

11b). The final arbiter of the juniper-pine boundary was again the forest-types map of

Andrews and Cowlin (1936). It was completed when juniper distribution was much

less extensive than today. The elevation of the change from grassland to pine woodland varies from 762 meters (2,500 ft) in the north, to 1525 meters (5,000 ft) along

the southern margin of the Ochocos, and 1400 to 1463 meters (4,600 to 4,800 ft) in

the interior John Day Valley. The “fuzzy boundary” or transition area between these

two regions estimates the extent of a juniper-pine mixed woodland.

The John Day-Clarno Highlands span a territory with the same east-west extent as

the John Day-Clarno subregion but at a higher elevational range. This subregion is

bounded by the eastward extent of the rain shadow of the higher peaks of the

Cascade Range. As a result of the mountainous barrier to marine weather systems,

the region exhibits a continental climate regime: little rain with wide extremes in annual and daily temperatures. The continental climate in this area, however, is moderated by a marine influence spreading southward from the Columbia Gorge and

westward through the low passes of the Cascade Range. The John Day-Clarno Highlands subregion is not as dry, nor are the temperature extremes as great, as they are

in the Continental Zone subregion of the southern Blue Mountains and the Continental Zone Foothills to the south and east (Loy and others 1991).

36
The soil moisture regime in this subregion is xeric, meaning that the soils are continuously dry for 60 to 90 days during summer. The soil temperature regime is frigid. In

the 6,600 years since the deposition of the Mount Mazama ash layer, erosion has

had a greater impact on these dry mountains of moderate elevation. With the ash

layer eroded away and no appreciable loess deposits, the water-holding capacity of

the soil is limited. Representative soils have a surface layer rich in organic matter,

with or without a clay-enriched subsoil. They are Ultic Argixerolls, Ultic Palexerolls,

and Lithic Ultic Haploxerolls.

The entire subregion is characterized by a predominance of ponderosa pine forest as

a potential vegetation cover. In the past, frequent low-intensity fires kept mesic forest

to a minimum distribution. Before fire suppression, true fir forests grew to maturity

only in moist areas that experienced few fires. As a result, serai ponderosa pine, and

to a lesser degree lodgepole pine and Douglas-fir, dominated the forest of this subregion early in this century. The trees grew in parklike stands, at a low enough density to avoid excessive moisture stress. Shade-tolerant young growth of true fir regenerated in the understory but did not survive the fires that recurred every 10 to 15

years (Hessburg and others 1994). Understory vegetation includes bitterbrush,

mountain-mahogany, bluebunch wheatgrass, pinegrass, and elk sedge.

The early forest type map (Andrews and Cowlin 1936) shows little late-successional

Mesic Forest (insert B, 111) in the John Day-Clarno Highlands subregion compared to

other subregions of the Blue Mountains. Only the Continental Zone of the south-central Blue Mountains has less true fir forest mapped. Along the spine of the Ochoco

Mountains, those peaks over 1830 meters (6,000 ft), for example, Wolf Mountain,

Peterson Point, and Mount Pisgah, have a true fir mantle. True fir also grows on the

north slopes of these and other major Ochoco peaks and near major springs between

1525 and 1830 meters (5,000 and 6,000 ft). The north slopes are a repository of

Mazama ash that provides the optimum growing medium for the grand fir.

Dry ponderosa pine forest and grassland penetrate almost 30 kilometers (50 mi) east

along the John Day River Valley from Picture Gorge to Prairie City, Oregon. There

the John Day-Clarno Formations and the Picture Gorge basalts meet the melange

geologic region, a chaotic collection of ocean sediments, deep sea crust, granitic

intrusions, and metamorphosed sediments and basalts, that constitute the core

of the central Blue Mountains. The change in geology plus a pronounced increase

in elevation at the Strawberry, Greenhorn, and Elkhorn Mountains mark the eastern

boundary of the John Day-Clarno Highlands subregion where orographic uplift of

weather systems and expansive high-elevation areas produce a significant extent

of mesic forest and subalpine parkland. Farther north, the John Day-Clarno Highlands

subregion meets the Maritime-Influenced Zone of the northern Blue Mountains.

Maritime-Influenced Zone—The Maritime-Influenced Zone (insert A, 11c; insert B,

11 c) is that part of the Blue Mountains that directly intercepts the marine weather

systems moving east through the break in the Cascade Range at the Columbia River

Gorge. The wet weather is intensified as the clouds rise up the slopes of the northern

Blue Mountains; rain and snow are delivered to these mountains three seasons of the

year. The maritime area receives more precipitation than anywhere else in the Blue

Mountains except the high Wallowas and Elkhorns (Loy and others 1991).

37
This ecological subregion is a mountainous continuation of the drier Columbia Plateau

to the north; it is composed of a lower elevation xeric forest surrounding large areas

of higher elevation mesic forest and a small area of subalpine parkland in the Blue

Mountains of southeastern Washington and in the northern Elkhorn Mountains.

Geologically, this zone is composed almost entirely of Columbia River basalts, except

for a bit of John Day and Clarno deposits in the far west and south. The uplifted

basalt plateau ranges in elevation from 915 to 2135 meters (3,000 to 7,000 ft). Mean

annual precipitation ranges from 58 centimeters (23 in) at the grassland-pine margin

to 100 centimeters (40 in) in the upper elevations of the upper Grande Ronde basin

to the south.

The soil of the region, however, is not a direct reflection of its basaltic parent material.

Much of northeast Oregon is covered by an ash mantle as much as 1 meter (40 in)

thick from the eruption of Mount Mazama in southwestern Oregon 6,600 years ago.

Glacier Peak and Mount St. Helens also contributed ash layers 12,000 and 10,000

years ago. Elsewhere in the Blue Mountains, in grassland areas and south-facing

slopes, much of this ash layer has eroded away; but this area, because of its adequate moisture, has had a constant vegetative cover and low fire incidence that

preserved the ash layer.

Because of the region’s proximity to the Columbia Plateau, there is also much loess

soil present, particularly in the lower elevation xeric forest and on the north slopes of

the northern Blue Mountains. Loess soil also has an increased water-holding capacity,

though not as great as ashy soil. The high nutrients, rock-free texture, and moist

microclimate of loess soil mean high productivity for the Idaho fescue and mesic

shrub associations (Johnson and Simon 1987). Douglas-fir also grows abundantly

on loessial soil. It is normally at a competitive disadvantage with ponderosa pine on

soils with little or no loess influence, but on loess soils, Douglas-fir is able to compete

successfully (Johnson and Simon 1987).

In the ponderosa pine woodland at the grassland-forest transition and in the adjoining

lower elevation forest, the soil moisture regime is xeric. The soils, Ultic Argixerolls,

Ultic Palexerolls, and Lithic Ultic Haploxerolls, have a surface layer rich in organic

matter with or without a clay-enriched subsoil. Because of the increased moisture

availability in the subregion generally, these xeric forests occur at a lower elevation

than elsewhere in the Blue Mountains. Ponderosa pine and bunchgrass associations

occur on south aspects at about 640 meters (2,100 ft) and pine-snowberry at 730

meters (2,400 ft). In canyons and in the forest understory, ninebark, serviceberry,

ocean-spray, and snowberry constitute a diverse shrub community that is able to regenerate after fire. Tree regeneration is sometimes delayed in the dense shrub layer

(Johnson and Clausnitzer 1992). Once established, however, Douglas-fir is resistant

to the constant movement of colluvial soils at canyon sites. The steep canyon slopes

at elevations of 700 to 1770 meters (2,300 to 5,800 ft) in this subregion are covered

with stands of Douglas-fir on soils formed in ash, loess, and basalt colluvium (Pachic

Ultic Haploxerolls and Vitrandic Argixerolls).

Mesic Forest Zone—Above about 762 meters (2,500 ft), in the Mesic Forest Zone

(insert B, 111) of the Maritime-Influenced ecoregion, the soil temperature regime is

still frigid, but the soil-moisture regime becomes more udic (moist). At the upper elevations of the Mesic Forest Zone, where moisture continues to increase, the soil temperature regime becomes colder in the cryic range. At mid and high elevations in this

region, the soil surface is composed of a thick mantle of volcanic ash, particularly on

38
north-facing slopes. These ashy soils may have a clay-enriched subsoil (Alfic

Udivitrands and Andic Eutroboralfs). Those without a clay subsoil are called Typic

Udivitrands. Soils on south-facing slopes, with more of the volcanic ash eroded

away, may be drier for a longer period of time. They are the Typic Vitrixerands and

Vitrandic Xerochrepts. Those soils with a clay-enriched subsoil are called Vitrandic

Haploxeralfs, and those with a dark surface layer rich in organic matter are Vitrandic

Haploxerolls.

Grand fir, Douglas-fir, lodgepole pine, Engelmann spruce, larch, and subalpine fir

all grow within the moisture and temperature ranges of the Mesic Forest Zone. Because of the relative lack of moisture stress and the nutrient value of the ash soil, forest productivity in the Maritime-Influenced Zone is higher than in other ecoregions of

the Blue Mountains. Larch, Douglas-fir, and lodgepole pine are the serai species;

historically, serai stands covered large areas at these elevations after wildfire. In the

late-serai grand fir forests, understory species range from twinflower and birchleaf

spirea in the drier end of the grand fir series at elevations as low as 762 meters

(2,500 ft), to Rocky Mountain maple or Pacific yew in the wettest areas, with big

huckleberry and grouse huckleberry associated on the highest, coldest sites (Johnson

and Clausnitzer 1992).

Subalpine Zone—The Subalpine Zone (insert B, 11m) in the Maritime-Influenced

Zone is limited to an area at the northern end of the Elkhorn range and scattered

areas of subalpine fir and ridgebrow grasslands in the Blue Mountains of southeastern Washington, particularly near Table Rock lookout. Johnson and Clausnitzer

(1992) list the elevation of subalpine fir in the north as 1400 to 1705 meters (4,600 to

5,600 ft). At its lower elevational limits, subalpine fir is a component of the closedcanopy mesic forest. It is difficult to find and map the point at which this forest cover

becomes patchy and interspersed with alpine meadows. As a result, subalpine areas

could be shown more extensively in the northern Blue Mountains, but most likely the

areas are too fragmented to be depicted on a map of this scale.

The boundary decisions for this subregion depend on tracking the limits of the marine

influence coming through the Columbia River Gorge from the west. The marine influence is evident first at Madison Butte and Tupper Butte in south-central Morrow

County, Oregon, with the appearance of areas of mesic fir forest. To the west, the

crest of the ridge is several hundred feet lower, just above 1524 meters (5,000 ft),

and the areas of climax grand fir forest disappear (Andrews and Cowlin 1936). This

is the point at which we pass out of the path of weather systems moving east through

the Columbia Gorge and into the shadow of the Cascade Range. From here east,

the northern boundary of this subregion is marked by the transition from Columbia

Plateau grassland to the moister higher elevation ponderosa pine woodland of the

Blue Mountains. To the south and west, the boundary between the MaritimeInfluenced Zone and the John Day-Clarno Highlands follows the convex slope of the

anticline of the northern Blue Mountains as it drops into the dry south-facing canyon

slopes of the North Fork of the John Day River. Farther south and east, the boundary

closely follows the ridgeline above the headwaters of the upper Grande Ronde River.

Though the marine influence would overlap the crest of the ridge to the south, the

geology also changes in this vicinity, from Columbia River basalts to the much more

complex geology of the central Blue Mountains, the Melange subregion.

39
Melange subregion—The Melange (insert A, 11d; insert B, 11d) subregion forms

the central core of the Blue Mountains. Webster’s Dictionary defines melange as a

“mixture of heterogeneous and often incongruous elements.” These are perfect

adjectives to describe the collection of limestone, marine mudstones, serpentinite and

peridotite, and the metamorphic greenstones and schists that make up the Elkhorn,

Greenhorn, Vinegar, and Aldrich Mountains.

Just as incongruous was the way in which these formations became a part of

Oregon’s land mass 100 million years ago. They are “accreted terranes,” that is,

chains of volcanic islands that collided with the continental margin, or portions of

dismembered oceanic crust that were scraped off by the conveyor-belt movement

of an oceanic plate diving beneath the continental crust at a subduction zone. In

the central Blue Mountains Melange subregion, a large piece of oceanic crust, an

ophiolite succession, composed of serpentine and peridotite, gabbro, dikes, pillow

lavas, and deep sea sediments (in that order!), constitutes Canyon Mountain above

John Day, Oregon (Hamblin 1985, Thayer 1990).

The soils over serpentine and other metamorphic rocks in the Blue Mountains can

be thin and rocky, particularly in erosional settings. They do not retain moisture,

and they create a hostile environment for plant growth, in part because of their high

magnesium content. Streams draining metamorphic areas dry up early in the season,

and xeric plant associations persist to higher elevations in metamorphic areas.

After their collision with the continental margin, the new lands were partially submerged by the accumulation of muds and sediments in Cretaceous seas. The sedimentary rocks in the Aldrich Mountains, rising south of John Day and Dayville, Oregon, are composed of thick deposits of shales and very fine sandstones (graywackes)

that accumulated to great depths in the ancient sea. They are more crumbly and

slightly more erodible than the argillites of the Elkhorn Mountains (Walker and

Robinson 1990). The soil from the graywackes is a well-drained gravelly loam soil

(Lithic Xerochrept) that supports ponderosa pine with fescue and Sandberg’s

bluegrass.

Scattered granitic bodies of Jurassic to Cretaceous age, about 90 to 140 million years

ago, have intruded the matrix of accreted terrane in the Melange subregion. Granite

intrusions have been exposed at Dixie Butte, Vinegar Hill, and the central and

northern Elkhorns. Gold and silver were discovered in the margins of the granitic

intrusions, and other precious metals have been mined from the metamorphic areas.

Placer mining altered the structure of many of the streams in the region. The town of

John Day is built on the tailings piles of a mining operation (Thayer 1990).

Above the older Paleozoic and Mesozoic Formations in the central Blue Mountains

are several thousand feet of ash and lava from widespread post-Cenozoic volcanism,

for example, the Clarno, John Day, Picture Gorge, and Strawberry Mountains volcanics. Beginning about 15 million years ago, these ranges, the Aldrich and Strawberry Mountains and ridges to the north, were compressed from both the north and

the south and uplifted along the John Day fault to form the folded topography evident

today (Thayer 1990, Walker 1990a).

40
By the end of the Pliocene period, only the highest peaks of the original accreted

terranes protruded through the various basalt and erosional layers; the early rocks

of the accreted terranes today constitute 10 to 15 percent of the mountainous area

of the Blue Mountains (Walker 1990a). Glacial activity during the Pleistocene then

sculpted the major peaks into cirques and amphitheaters, shaped valleys above

1525 meters (5,000 ft), and left major sedimentary deposits in valley bottoms

(Thayer 1990).

At the lowest forested elevations 1372 to 1525 meters (4,500 to 5,000 ft) in the

Melange subregion (insert B, 11d), ponderosa pine and juniper grow in an open forest above a diverse shrub understory of mountain-mahogany, bitterbrush, and squaw

currant. In higher, cooler sites, Douglas-fir is codominant with ponderosa pine with

the same understory plants. At the highest elevational ranges for Douglas-fir, on dry

slopes and ridgetops approaching 1677 meters (5,500 ft), a Douglas-fir/pinegrass or

Douglas-fir/snowberry association may be found. Recurring fire favors the persistence

of ponderosa pine with a pinegrass or elk sedge understory (Johnson and Clausnitzer

1992). All these associations are adapted to grow on metamorphic substrate; the

droughtiness of the soil may be ameliorated by a thin mantle of ash or loess.

The eastern Strawberry Mountains differ from the older accreted terranes of the

Melange subregion in that they are composed of mostly younger basalt and andesites. The residual soil from the basalt and andesite substrate differ from ash and

loessial soil in that they have a finer texture in the upper profile, coarser fragments in

the soil matrix, and a lower moisture-holding capacity, resulting in a wide elevational

range of ponderosa pine- and Douglas-fir-dominated forest. Where an ash layer is

present, the productivity of the soil increases and grand fir is able to grow. The soils

in this zone have a frigid temperature regime and a xeric moisture regime. The mixed

forest soils, with or without an ash layer or a clay-enriched subsoil, include Typic

and Alfic Vitrixerands, Vitrandic and Ultic Haploxeralfs, and Vitrandic and Dystric

Xerochrepts. Under the more xeric, ponderosa pine forest in the lower elevations,

soils form from basalt residuum and colluvium and have a surface layer high in

organic matter; they may or may not have a clayey subsoil (Vitrandic, Lithic and

Lithic Ultic Haploxerolls, Lithic and Typic Argixerolls).

Mesic Forest Zone—In the Elkhorn Mountains, at elevations surrounding the subalpine and alpine core, the Mesic Forest Zone here (insert B, 111) resembles that of

the Maritime Influenced subregion (insert B, 11 c) to the north. The difference is that

the area is outside of the direct influence of the marine weather. These mountains

receive adequate precipitation, (up to 85 centimeters [35 in]) to support a true fir

forest community because of orographic uplift on the west slopes above the John

Day basin. The soil-moisture regime here is drier than in the maritime-influenced

area, but the onset of moisture stress is delayed by a moisture-retaining ash mantle.

Characteristic soils in this Mesic Forest Zone (insert B, 111) are Typic and Alfic

Vitrixerands, Vitrandic and Ultic Haploxeralfs, and Vitrandic and Dystric Xerochrepts.

41
Subalpine Zone—At elevations above 1585 meters (5,200 ft) in the Elkhorns and

about 1700 meters (5,600 ft) in the Strawberry Mountains, a subalpine forest zone

(insert B, 11m) of subalpine fir, lodgepole pine, and Engelmann spruce grades into

whitebark pine and alpine sagebrush openings, and finally into alpine meadows at

about 2285 meters (7,500 ft). Soils with a thick ash mantle are classified as Typic

Vitricryands, with a thin ash mantle, Andic Cryumbrepts, and with a thin ash mantle

and a clay-enriched subsoil, Andic Cryoboralfs. These soils are cryic and udic (moist).

In alpine meadows, the soils may be shallow, Lithic Cryumbrepts and Cryochrepts,

or moderately deep with a thin ash mantle and an organic-matter rich surface (Andic

and Vitrandic Cryumbrepts).

Wallowas-Seven Devils subregion—The Wallowas-Seven Devils range (insert A,

11e; insert B, 11e) began as a volcanic island arc in a warm, low-latitude sea. As the

North American Continent was set in motion westward by the widening of the midAtlantic rift 200 million years ago, a subduction zone developed at the western edge

of the continent in what is now western Idaho. As the North American plate moved

westward, it collided with and overran the complex island arc system to form the

earliest Oregon land mass. Geologists have pieced together the evidence of this

genesis from the collage of ocean sediments, limestone reef formations, and slightly

metamorphosed lavas (greenstones) that form the Wallowas and the Seven Devils

Mountains. The Martin Bridge limestone crops out in the cliffs along the Lostine River,

on Marble Mountain, and the Matterhorn. The dark sedimentary rocks and volcanic

greenstones compose many of the intermediate ridges and peaks in the high

Wallowas. Today, some of the perimeter sediments are folded from their traumatic

collision with the edge of the continent. Fossil shells attest to their oceanic origins.

The ancient ocean sediments and volcanic debris have been peeled away from

the center of the Wallowas through erosion; they surround the perimeter of a large

granitic intrusion that forms the central core of the Wallowas. Earlier writers, for example, Baldwin (1976), suggested that this granitic batholith was related to the Idaho

batholith to the east that is 75 to 100 million years old. Goldstrand (1994), however,

places the age of the Wallowa batholith as 143 to 160 million years, older than the

Idaho batholith.

Finally, to complete the geologic setting of the Wallowas-Seven Devils area, the

granitic core and the remains of the island arc terrane surrounding it, rise above

a sea of Columbia River basalt, which flooded the area 12 to 15 million years ago.

Although much of the Columbia River basalt has eroded away, it still caps prominent

peaks in the Wallowas; for example, Chief Joseph, Aneroid, and Twin Peaks.

Following the long episode of accumulation of many strata of flood basalts, the

Wallowas were uplifted by faulting on two sides. The fault system responsible for

the uplift is still active today. The entire Wallowa region is a horst or upthrust block

(Bishop 1995). The fault on the north side of the range is most evident. There the

escarpment is steep, particularly above 2285 meters (7,500 ft) (Smith and others

1941). Except for some overlapping sediments and slumping on the north side, the

line between the Blue Mountains ecoregion and the Columbia Plateau, here represented by the greater Wallowa Valley, is sharply delineated. The cold air drainage from the mountains and rain-shadow effect gives the local Wallowa Valley

climate continental extremes in temperature and precipitation.

42
The soils are a mixture of colluvial canyon soil and soil with a loess or ash mantle.

Because of the presence of loess and ash, the xeric forest zone is relatively narrow

and soon grades into a mixed ponderosa pine, Douglas-fir, western larch, and grand

fir forest. The plateau soils are frigid and usually moist (udic). They are classed as

Typic Udivitrands if they have a mantle of volcanic ash without a clay subsoil and as

Alfic Udivitrands, Andic, or Vitrandic Eutroboralfs if they have a clay-enriched subsoil.

Often on southern aspects in this region the dominant vegetation changes from

bunchgrasses directly to Douglas-fir without an intervening ponderosa pine phase.

This is partly due to the loess content of the soil. Douglas-fir has an affinity for loess

and its additional moisture-retaining capacity. Also, Douglas-fir is adapted to growing

in the difficult environment of shifting colluvial soils on steep canyon slopes.

All areas of the Canyons and Dissected Highlands subregion border the Canyons

and Dissected Uplands subregion of the Columbia Plateau except for the east side

of Summit Ridge east of the Wallowa Mountains, where the terrain dives into the

canyon depths of the Snake and Salmon River Canyons (insert B, 11g).

Snake and Salmon River Canyons—The Columbia River flood basalts buried

the accreted terranes 13 to 16 million years ago, leaving only the highest Wallowas

and Seven Devils Mountains protruding. The basalt dams blocked the flow of the

ancestral Snake River, creating Lake Idaho. About 2 million years ago, headward

erosion and stream capture created the present Snake River channel between Boise

and Lewiston, Idaho. The drainage of Lake Idaho carved Hell’s Canyon to expose

the foundation rocks of the Blue Mountains, the stranded islands of the island arc

terrane. During the Pleistocene, the emptying of Lake Bonneville widened and

deepened the Snake River Canyon (Johnson and Simon 1987). The topographic

relief at Hell’s Canyon is 1525 meters (5,000 ft) from the river to the tops of the

Seven Devils Mountains, making it the deepest canyon in the United States.

The Snake and Salmon River Canyons (insert A, 11g; insert B, 11g) subregion is a

continuation of a similar subregion, the Canyons and Dissected Uplands, in the

Columbia Plateau ecoregion to the north (see section 1, above). It was an option to

retain these two canyons as part of the Canyons and Dissected Uplands subregion

of the Columbia Plateau. The two subregions have a similar erosional pattern, a

parallel series of knife-edged ridges cut into the basalt. They also have similar

climate, precipitation pattern, and grassland vegetation. The climate in the canyon is

hot and dry, with mild winters. Precipitation ranges from 25 to 50 centimeters (10 to

20 in) annually.

The Snake and Salmon River Canyons have been included in the Blue Mountains

ecoregion in part because of their geographic location, surrounded as they are by

the Wallowas and Seven Devils Mountains. In addition, these canyons differ from

those to the north in the Columbia Plateau ecoregion by the presence, under a

thick covering of Columbia River basalt, of metasedimentary and metavolcanic

rock belonging to the Wallowa-Seven Devils island arc terrane that became part

of the continent 100 million years ago.

43
These metamorphic rocks may produce deep soils on river benches; however, the

soil is stony and retains little moisture. Bluebunch wheatgrass, Sandberg’s bluegrass,

and spiny greenbush are adapted to grow under these hot, dry conditions (Johnson

and Simon 1987). Canyon slopes with a favorable northern aspect may have a

covering of loess. Loess retains moisture better than colluvial soil; it fosters Idaho

fescue associations and more mesic shrubs such as rose and snowberry (Johnson

and Simon 1987).

The soils over the Miocene basalt flows are divided by elevation into those below

1067 meters (3,500 ft) with a mesic temperature regime and those above 1067

meters (3,500 ft) with a frigid temperature regime. Below 1067 meters (3,500 ft),

the aridic and xeric soils are dominated by Lithic, Aridic, and Typic Haploxerolls.

Above 1067 meters (3,500 ft), the xeric soils in the cooler temperature zone are

Lithic and Pachic Argixerolls and Lithic Haploxerolls. Vegetationally, bluebunch

wheatgrass and Sandberg’s bluegrass are adapted to the driest areas; Idaho fescue

dominates in the increased moisture of the middle to higher elevations, becoming

mixed with snowberry and scattered ponderosa pine at the upper end of the canyons.

Continental Zone Highlands—The Continental Zone Highlands (insert B, 11h) comprise the south-central and southeastern Blue Mountains, those areas most in the

continental climate regime. Low precipitation, high evapotranspiration, abundant sunshine, and temperature extremes of 37.7 to -23.3 °C (100 to -10 °F), characterize the

climate pattern in this section of the Blue Mountains. The stream density is less than

elsewhere in the Blue Mountains, and intermittent streams are more numerous. The

few major streams flowing south end in the interior drainage of the Harney basin. The

topography is not as steep as elsewhere in the Blue Mountains; it is an undulating

landscape with broad open flats and stringers of woodland distributed up the draws.

Isolated mountain peaks and buttes dot the landscape. Elevations range from 1067

meters (3,500 ft) to near 2135 meters (7,000 ft) (Paulson 1977).

The geology of the area also is different from regions to the north. Recent volcanics

of Pliocene age, rhyolites and ash flow tuffs, cover these southern mountains as well

as areas far to the south to northern Nevada (Walker 1990b, Walker and MacLeod

1991). Rhyolite is a moderately hard rock resistant to weathering. Consequently, the

soil formed from residuum and colluvium of rhyolite is often shallow and cobbly or

gravelly. Most of the soils in this subregion are in the xeric soil moisture regime and

in the frigid soil temperature regime. In the lower elevations, where ponderosa pine is

the climax species, the major soil subgroups are Vitrandic and Lithic Haploxerolls as

well as Lithic and Typic Argixerolls.

The vegetation cover of the Continental Zone has similarities to the central Blue

Mountains and the southern Ochocos in the ponderosa pine-xeric shrub-bunchgrass

associations. Ponderosa pine forest occupies the warmest, driest zones; it is the

climax species in the lower elevations. The pine grows on a wide range of soils in a

zone from 762 to 1675 meters (2,500 to 5,500 ft) where the mean annual precipitation is 41 to 89 centimeters (16 to 35 in). At about 1370 meters (4,500 ft), the scattered pine-grassland savannah becomes a more closed-canopy woodland with pine

and juniper mixed with xeric shrubs. The most common xeric shrubs are big sage,

mountain-mahogany, bitterbrush, and squaw currant. These pine-shrub associations

44
are found at elevations of 1220 to 1675 meters (4,000 to 5,500 ft). Of the understory

plants, big sage indicates a very dry site, mountain-mahogany indicates a stony, lowproductivity site, and bitterbrush a site higher in productivity (Hall 1973, Johnson and

Clausnitzer 1992).

The especially early drought on xeric, ashy soil also produces several distinctive associations that are shrubfree. They are the ponderosa pine or Douglas-fir with pinegrass and elk sedge associations. Both plants are promoted by fire, but pinegrass

prefers ash soil. These associations are found on southern exposures on droughty, thin

soil from 1220 to 1980 meters (4,000 to 6,500 ft).

There is no appreciable Mesic Forest subregion in the upper elevations of the Continental Zone Highlands as there is in the other subregions of the Blue Mountains. In

the higher elevations, grand fir is technically the climax with pinegrass and elk sedge

understories. Normally, however, the grand fir rarely matures because of the fire

frequency (Hall 1973, Johnson and Clausnitzer 1992). Douglas-fir and grand fir associations do form a mixed forest at the moist end of the xeric soil moisture gradient.

Douglas-fir climax associations may be found from 1220 to 1705 meters (4,000 to

5,600 ft) on all parent materials.

Continental Zone Foothills—The Continental Zone Foothills (insert B, 11i) subregion

bounds the southern perimeter of the Blue Mountains from a point near the southeast

corner of Crook County on the southern flanks of the Ochoco Mountains, around the

east side of the Elkhorn Mountains and Baker Valley, to the edge of the massive

batholith in western Idaho. Elevations range from 1067 to 1615 meters (3,500 to

5,300 ft) in the eastern portion and from 1370 to 1585 meters (4,500 to 5,200 ft) in

the west. Precipitation ranges from 25 to 40 centimeters (10 to 16 in), increasing with

increasing elevation. The precipitation falls as light snow, spring or fall rains, or occasional summer thunderstorms. Land use is predominantly grazing, except in the

irrigated valleys.

Geologically, the Continental Zone Foothills have three major subdivisions. The foothills from the Ochoco Mountains to the Willow Creek Valley (near the Baker CountyMalheur County line) form the first unit. They are underlain by lava flows and breccia

of Miocene basalt and andesite. These volcanics cover a large area of the high desert

in Oregon south to the Nevada border.

The second geologic subdivision, the hills and terraces bordering the Baker Valley

area, south of the Wallowa Mountains to the Snake River canyon, is a continuation

of the melange geology of the central Blue Mountains. The geologic landscape is a

chaotic collection of volcanic island arc fragments, deep sea crust and sediments,

and granitic intrusions, overlain in the south and east by Miocene basalts and

andesites of the Powder River volcanics.

Finally, an arm of the Blue Mountains east of the Snake River extends south above

the Snake River Plain to just north of Boise, Idaho. Geologically, this area is the

southernmost extension of the Miocene flood basalts that inundated the Columbia

Plateau. The basalt filled the topographic trough that follows the “suture zone” of the

new (200 million years old) accreted terrain and the ancient continental land mass.

The flood basalt also blocked the flow of the Miocene Snake River to create Lake

Idaho. The southern foothills, running south of Huntington, Oregon, and east into

Idaho, end at the margin of the valley sediments deposited in Lake Idaho, what is

now the Snake River Plain.

45
Ecologically, however, geologic makeup is subordinate to the other landscape characteristics that make this subregion distinctive. The ecosystem is a reflection of the consistency of the climate, soil, and vegetation cover. The entire area is solidly within the

continental climate zone. The combined land masses of the Cascade Range and the

Blue Mountains to the northwest effectively block any marine influence. As a result,

the Continental Zone Foothills subregion experiences wide temperature ranges, xeric

and aridic soil regimes, high evapotranspiration, and high early season moisture

stress for vegetation. The few perennial streams draining the Ochocos and Malheur

Mountains empty into the marshes of the Harney basin to the south. To the east, the

subregion is surrounded by higher mountain ranges, the Elkhorns and Wallowas, and

thus has more perennial streams; but up away from the streams, the upland areas

have even drier soil regimes than the foothills farther west.

The soils of the western portion of the foothills region have basalts, andesites, and

rhyolites as parent material. They are shallow to moderately deep soils with xeric

moisture and frigid temperature regimes. The dominant soil families are Typic, Lithic,

and Pachic Argixerolls as well as Lithic Haploxerolls. The surface layer of these soils

is typically stony loam with a gravelly clay loam subsoil.

The soils of the eastern foothills with mixed geology are deeper in general than those

to the west, except on the steeper hill slopes. The soils on terraces below an elevation of about 1220 meters (4,000 ft) have an aridic moisture and a mesic temperature

regime. The soils above 1220 meters (4,000 ft) have a xeric moisture and a frigid

temperature regime. The surface layer is typically a silt loam or loam with a clay loam

or clay subsoil. The soil families on the lower terraces are Aridic and Aridic Calcic

Argixerolls, Xeric Argidurids, and Xeric Haplocambids. On the higher terraces, the

soils often have a hardpan or dense clay layer within 1 meter (40 in) of the soil surface. Here the major orders are Typic and Pachic Palexerolls and Typic Durixerolls.

The rolling hills between the Baker Valley and the Snake River Canyon and farther

east into Idaho have shallower, more cobbly soils. They are classed as Calcic, Lithic,

Typic, and Pachic Argixerolls.

The vegetation of the Continental Zone Foothills is characterized by a diverse desert

shrub community that differs according to the soil depth, texture, and productivity.

The poorest sites, with shallow soil, winter waterlogging, and desert pavement, grow

stiff sagebrush or low sage with some juniper on the scabland “biscuits.” Mountainmahogany grows on rocky sites in a wide elevational range. Somewhat deeper soils

over varied substrate will support bitterbrush, mountain snowberry, and mountain big

sage with bunchgrasses in associations. Both mountain-mahogany and bitterbrush

are valuable wildlife resources, providing cover and winter range for mule deer.

Rodents, passerines, and upland game birds use the fruits and buds of bitterbrush

(Johnson and Clausnitzer 1992). Bitterbrush decreases to the east where it becomes

scarce on the southern flanks of the Wallowas (Johnson and Simon 1987).

Batholith Contact Zone—In westernmost Idaho, an arm of the Blue Mountains, the

Batholith Contact Zone (insert B, 11j), forms the transition from the dry Snake River

Plains to the northern Rocky Mountains. This area is included with the Blue Mountains because its climate, geology, soil, and vegetation are consistent with those elsewhere in the Blue Mountains. There is still a slight marine influence from the northwest in this area; the climate becomes more extreme to the east. The moderated

46
climate, along with soils developed from the basaltic parent material, produces a

typically Blue Mountains vegetation. Elevations range from about 1370 to 2530

meters (4,500 to 8,300 ft), high enough for a Mesic Forest Zone and a Subalpine

Zone. This is the southeastern limit of the Columbia River basalts. The region is

transitional because it bridges the Columbia River basalts and the massive Idaho

granitic batholith; the rock has been highly metamorphosed to schists, amphibolite,

and greenstones (McKee 1972).

Ponderosa pine dominates the forest community between 914 and 1980 meters

(3,000 and 6,500 ft). Its upper limits are determined in part by the depth of snowpack.

In this transitional area, Douglas-fir assumes a similar role to the one it takes farther

north in the Canyons and Dissected Highlands subregion. It is found on north-facing

slopes from 945 to 2164 meters (3,100 to 7,100 ft) on various substrate with an

understory of ninebark. It is adapted to the more mesic conditions there as well

as the colluvial soils of the canyons (Steele and Geier-Hayes 1989). A Douglasfir/pinegrass association also is prevalent in this zone of slight maritime influence

(Steele and Geier-Hayes 1987).

Mesic Forest Zone—Above 1525 meters (5,000 ft) in the Mesic Forest Zone (insert

B, 111), grand fir and blue huckleberry grow on both granitic and volcanic substrate,

between 1525 and 1890 meters (5,000 and 6,200 ft). Again, due to the slight residual

marine influence, this area is the southeastern outpost for grand fir (Steele and

Geier-Hayes 1987). The major portion of the Mesic Forest Zone occurs on the northwestern to northeastern aspects. The common serai species in the Mesic Forest Zone

are ponderosa pine, western larch, lodgepole pine, and Engelmann spruce.

Blue Mountains Basins—The Blue Mountains Basins, (insert A, 11k; insert B, 11k)

ecoregion is a composite region composed of scattered basins large enough to be

depicted at the 1:250,000 scale. Structurally, the basins may be the result of depressions or synclinal downwarps in the flow sequences of the flood basalts (for example,

Ukiah and John Day basins), erosion of a soft substrate in ash or tuff areas (Fox

basin), or depressions defined by faults (Grande Ronde and Baker Valleys).

Pyroclastic rocks and tuffaceous sedimentary rocks were deposited in many basins,

for example, the John Day, Fox, Bear, and Logan Valleys. The John Day basin was

filled with gravelly, sedimentary rocks from the rising Aldrich and Strawberry Mountains. Airborne ashfall tuff characterizes the basins of the southern perimeter of the

Blue Mountains, Baker Valley, the Durkee and Unity basins, Paulina and Burnt

Rivers, and the lower Powder River Valley (Walker 1990b).

The Grande Ronde Valley, near La Grande in northeastern Oregon, is a faultbounded valley graben. Hot springs, such as those at Hot Lake, are present around

the periphery of the valley, thereby indicating that geologic unrest is continuing. The

basin is deep to bedrock, filled with up to 610 meters (2,000 ft) of sediments to its

present-day elevation of 785 to 850 meters (2,600 to 2,800 ft). The valley fill consists

of various Pleistocene deposits of gravels and silts, lacustrine deposits, alluvial fans,

and loess from the Columbia Plateau to the north. The lake bed silts are still poorly

drained; they are classified as Haploxerolls, Endoaquolls, and Haplaquolls. Settlers

47
drained most of the marshland for pasture and hay, but there is a remnant left in the

southwestern valley at Ladd Marsh. The valley also has a significant deposit of loess

running from the central valley to its northern edge. The soils here are deep to

bedrock; they are classed as Haploxerolls, Argialbolls, and Argixerolis. The potential

natural vegetation on the terraces and loess hills consists of Idaho fescue, common

snowberry, and Sandberg’s bluegrass. On the flood plains, tufted hairgrass, redtop,

and sedges are associated with wetter soils. Today, most of the valley is farmed. The

Grande Ronde River and its tributary streams, many of which have been channelized,

provide irrigation water to grow hay, commercial grass seed, alfalfa, and peas.

The Grande Ronde Valley is transitional to the dryer, loess covered, Columbia Plateau to the north; however, structurally the valley is wedded to the Wallowa Mountains. Also, the climate of the valley is still moderated by the marine influence from

the west. Precipitation amounts range from 32.5 centimeters (13 in) in the dry southern valley to 60 centimeters (24 in) at the eastern end of the valley. For these reasons, the valley was included in the Blue Mountains ecoregion rather than in the

Columbia Plateau.

The Baker Valley of the eastern Blue Mountains is also a fault-bounded depression

in the melange geology of the Baker terrane (see the geologic explanation under the

Melange subregion). Elevations range from 610 to 1675 meters (2,000 to 5,500 ft).

The valley and surrounding grasslands encompass the alluvial flood plains and terraces of the Burnt and Powder Rivers. The basin is in an arid area of continental climate. The mean annual precipitation ranges from 23 centimeters (9 in) in the lower

elevations to 40 centimeters (16 in) on the higher terraces. Soils below 1220 meters

(4,000 ft) have an aridic soil moisture regime, meaning they receive less than 25

centimeters (10 in) of precipitation annually. The aridic soils also have a warmer temperature regime (mesic). The east edge of the basin has abundant alkaline soils due

to poor drainage and high evaporation rates. The shrub greasewood is abundant

there. The flood-plain soil is deep silt loam or silty clay loam, classified as Pachic

Haploxerolls or Typic Haplaquepts. Soils on the terraces include Aridic Argixerolis,

Xeric Argidurids, and Xeric Haplocambids.

Finally, many of the scattered depressions filled with airborne ash and pyroclastic volcanic debris constitute the high-elevation meadows. The high meadows are often also

alluvial, with a high water table and with soils containing clay or silt. Streams are slow

and meandering, and if not channelized, they have a dynamic interaction with their

flood plains. These unconstrained sections of stream provide pool habitats so important to salmonids for refuge and rearing (Mclntosh and others 1994). The altitude and

year-round moisture make these basins unsuitable for cultivation, but they are grazed

heavily by cattle and elk. The vegetation includes sedges and tufted hairgrass. Meadows in poor condition are dominated by Kentucky bluegrass (Poa pratensis L). The

riparian areas, if still present, support willow. Trampling and overgrazing on the fine

silty substrate may cause the incision of the stream bed, lowering the water table and

stranding the wet meadow without a source of ground water.

48
Literature Cited Alt, D.D.; Hyndman, D.W. 1978. Roadside geology of Oregon. Missoula, MT:

Mountain Press Publishing Co. 268 p.

Anderson, E.W. 1956. Some soil-plant relationships in eastern Oregon. Journal of

Range Management. 9(4): 171-175.

Andrews, H.J.; Cowlin, R.W. 1936. Forest type map of Oregon: northeast quadrant.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Experiment Station. 1:253,440.

Baldwin, E.M. 1976. Geology of Oregon. Dubuque, IA: Kendall/Hunt Publishing

Company. 147 p.

Bishop, E.M. 1995. Mafic and ultramafic rocks of the Baker Terrane. In: Vallier, T.L.;

Brooks, H., eds. Geology of the Blue Mountains region. Professional Pap. 1438.

[Place of publication unknown]: U.S. Department of the Interior, Geological

Survey: 221-245.

Brooks, H.C. 1979. Plate tectonics and the geologic history of the Blue Mountains.

Oregon Geology. 41(5): 71-80.

Fifarek, R.H.; Juhas, A.P.; Field, C.W. 1994. Geology, mineralization, and alteration

of Red Ledge volcanogenic massive sulfide deposit, western Idaho. In: Vallier,

T.L.; Brooks, H.C., eds. Geology of the Blue Mountains region of Oregon, Idaho,

and Washington: stratigraphy, physiography, and mineral resources of the Blue

Mountains region. Professional Pap. 1439. Washington, DC: U.S. Department of

the Interior, Geological Survey; U.S. Government Printing Office: 113-150.

Goldstrand, P.M. 1994. The Mesozoic geologic evolution of the north Wallowa

terrane, northeast Oregon and western Idaho. In: Vallier, T.L.; Brooks, H.C., eds.

Geology of the Blue Mountains region of Oregon, Idaho, and Washington:

stratigraphy, physiography, and mineral resources of the Blue Mountains Region.

Professional Pap. 1439. Washington, DC: U.S. Department of the Interior,

Geological Survey; U.S. Government Printing Office: 29-53.

Hall, F.C. 1973. Plant communities of the Blue Mountains of eastern Oregon and

southeastern Washington. Pacific Northwest Region Area Guide 3-1. Portland,

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region.

62 p.

Hamblin, W.K. 1985. The Earth’s dynamic systems: a textbook in physical geology.

Minneapolis, MN: Burgess Publishing. 528 p.

Harvey, A.E.; Geist, J.M.; McDonald, G.I. [and others]. 1994. Biotic and abiotic

processes in eastside ecosystems: the effects of management on soil properties,

processes, and productivity. Gen. Tech. Rep. PNW-GTR-323. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Research Station.

71 p. (Everett, Richard L, assessment team leader; Eastside forest ecosystem

health assessment; Hessburg, Paul F., science team leader and tech. ed.,

Volume III: assessment).

49
Hessburg, P.F.; Mitchell, R.G.; Filip, G.M. 1994. Historical and current roles of

insectsand pathogens in eastern Oregon and Washington forested landscapes.

Gen. Tech. Rep. PNW-GTR-327. Portland, OR: U.S. Department of Agriculture,

Forest Service,Pacific Northwest Research Station. 72 p. (Everett, Richard L.,

assessment team leader; Eastside forest ecosystem health assessment;

Hessburg, Paul F., science team leader and tech. ed., Volume III: assessment).

Hooper, P.; Swanson, D. 1990. The Columbia River basalt group and associated

volcanic rocks of the Blue Mountains province. In: Walker, G., ed. Geology of the

Blue Mountains region of Oregon, Idaho, and Washington: Cenozoic geology of

the Blue Mountains region. Professional Pap. 1437. Washington, DC: U.S. Department of the Interior, Geological Survey; U.S. Government Printing Office: 63-101.

Irwin, L.; Cook, J.G.; Riggs, R.A.; Skovlin, J.M. 1994. Effects of long-term grazing

by big game and livestock in the Blue Mountains forest ecosystems. Gen. Tech.

Rep. PNW-GTR-325. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station. 49 p. (Everett, Richard L., assessment team leader; Eastside forest ecosystem health assessment; Hessburg,

Paul F., science team leader and tech. ed., Volume III: assessment).

Johnson, C.G., Jr. 1994. Forest health in the Blue Mountains: a plant ecologist’s

perspective on ecosystem processes and biological diversity. Gen. Tech. Rep.

PNW-GTR-339. Portland, OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Research Station. 24 p. (Quigley, Thomas M., ed.; Forest health

in the Blue Mountains: science perspectives).

Johnson, C.G., Jr.; Clausnitzer, R.R. 1992. Plant associations of the Blue and

Ochoco Mountains. Publ. R6-ERW-TP-036-92. La Grande, OR: U.S. Department

of Agriculture, Forest Service, Pacific Northwest Region, Wallowa-Whitman

National Forest. 163 p.

Johnson, C.G., Jr.; Clausnitzer, R.R.; Mehringer, P.J.; Oliver, C.D. 1994. Biotic

and abiotic processes of eastside ecosystems: the effects of management on

plant and community ecology, and on stand and landscape vegetation dynamics.

Gen. Tech. Rep. PNW-GTR-322. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research Station. 66 p. (Everett, Richard L.,

assessment team leader; Eastside forest ecosystem health assessment;

Hessburg, Paul F., science team leader and tech. ed., Volume III: assessment).

Johnson, C.G., Jr.; Simon, S.A. 1987. Plant associations of the Wallowa-Snake

province. Wallowa-Whitman National Forest Publ. R-6 ECOL-TP-225A-86.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Region. 400 p.

Kagan, J.; Caicco, S. 1992. Manual of Oregon actual vegetation. Boise, ID: Idaho

Cooperative Fish and Wildlife Research Unit, University of Idaho. 186 p.

Lehmkuhl, J.F.; Hessburg, P.F.; Everett, R.L. [and others]. 1994. Historical and

current forest landscapes of eastern Oregon and Washington. Part 1: Vegetation

pattern and insect and disease hazards. Gen. Tech. Rep. PNW-GTR-328.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Research Station. 88 p. (Everett, Richard L, assessment team leader; Eastside

forest ecosystem health assessment; Hessburg, Paul F., science team leader and

tech. ed., Volume III: assessment).

50
Loy, W.G.; Allen, S.; Patton, C.P.; Plank, R.D., eds. 1991. Atlas of Oregon.

Eugene, OR: University of Oregon. 344 p.

Mclntosh, B.A.; Sedell, J.R.; Smith, J.E. [and others]. 1994. Management history

of eastside ecosystems: changes in fish habitat over 50 years, 1935 to 1992. Gen.

Tech. Rep. PNW-GTR-321. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station. 55 p. (Everett, Richard L,

assessment team leader; Eastside forest ecosystem health assessment;

Hessburg, Paul F., science team leader and tech. ed., Volume III: assessment).

McKee, B. 1972. Cascadia. Seattle, WA: Stuart Press. 394 p.

Oliver, C.D.; Irwin, L.L.; Knapp, W.H. 1994. Eastside forest management practices:

historic overview, extent of their applications, and their effects on sustainability of

ecosystems. Gen. Tech. Rep. PNW-GTR-324. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Research Station. 73 p. (Everett,

Richard L., assessment team leader; Eastside forest ecosystem health

assessment; Hessburg, Paul F., science team leader and tech. ed., Volume III:

assessment).

Orr, E.L.; Orr, W.N.; Baldwin, E.M. 1992. Geology of Oregon. 4th ed. Dubuque, IA:

Kendall/Hunt Publishing Co. 254 p.

Paulson, D.J. 1977. Ochoco National Forest soil resource inventory. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 347 p.

Retallack, G.J. 1991. A field guide to mid-Tertiary paleosols and paleoclimatic

changes in the high desert of central Oregon. Part 1. Oregon Geology. 53(3):

51-59.

Robbins, W.G.; Wolf, D.W. 1994. Landscape and the intermontane northwest: an

environmental history. Gen. Tech. Rep. PNW-GTR-319. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 32 p.

(Everett, Richard L., assessment team leader; Eastside forest ecosystem health

assessment; Hessburg, Paul F., science team leader and tech. ed., Volume III:

assessment).

Robinson, P.T.; Walker, G.W.; McKee, E.H. 1990. Eocene, Oligocene, and lower

Miocene rocks of the Blue Mountains region. In: Walker, G., ed. Geology of the

Blue Mountains region of Oregon, Idaho, and Washington: Cenozoic geology of

the Blue Mountains region. Professional Pap. 1437. Washington DC: U.S.

Department of the Interior, Geological Survey; U.S. Government Printing Office:

29-62.

Skovlin, J.M. 1991. Fifty years of research progress: an historical document on the

Starkey Experimental Forest and Range. Gen. Tech. Rep. PNW-GTR-266.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Research Station. 58 p.

Smith, W.D.; Allen, J.E.; Staples, L.W.; Lowell, W.R. 1941. Geology and physiography of the northern Wallowa Mountains, Oregon. Bull. 12. Salem, OR: State of

Oregon, Department of Geology and Mineral Industries. 55 p.

51
Steele, R.; Geier-Hayes, K. 1987. The grand fir/blue huckleberry habitat type in

central Idaho: succession and management. Gen. Tech. Rep. INT-228. Ogden,

UT: U.S. Department of Agriculture, Forest Service, Intermountain Research

Station. 66 p.

Steele, R.; Geier-Hayes, K. 1989. The Douglas-fir/ninebark habitat type in central

Idaho: succession and management. Gen. Tech. Rep. INT-252. Ogden, UT: U.S.

Department of Agriculture, Forest Service, Intermountain Research Station.

Thayer, T. 1990. Geologic setting of the John Day country, Grant County, Oregon.

[Place of publication unknown]: [Publisher unknown]. 23 p.

Walker, G. 1990a. Miocene and younger rocks of the Blue Mountains region. In:

Walker, G., ed. Geology of the Blue Mountains region of Oregon, Idaho, and

Washington: Cenozoic geology of the Blue Mountains region. Professional Pap.

1437. Washington, DC: U.S. Department of the Interior, Geological Survey; U.S.

Government Printing Office: 101-119.

Walker, G. 1990b. Overview of the Cenozoic geology of the Blue Mountains. In:

Walker, G., ed. Geology of the Blue Mountains region of Oregon, Idaho, and

Washington: Cenozoic geology of the Blue Mountains region. Professional Pap.

1437. Washington, DC: U.S. Department of the Interior, Geological Survey; U.S.

Government Printing Office: 1-12.

Walker, G.W.; MacLeod, N.S. 1991. Geologic map of Oregon. Denver, CO: U.S.

Department of the Interior, Geological Survey. 1:500,000. (two sheets).

Walker, G.; Robinson, P.T. 1990. Cenozoic tectonism and volcanism of the Blue

Mountains region. In: Walker, G., ed. Geology of the Blue Mountains region of

Oregon, Idaho, and Washington: Cenozoic geology of the Blue Mountains region.

Professional Pap. 1437. Washington, DC: U.S. Department of the Interior,

Geological Survey; U.S. Government Printing Office: 119-133.

White, J.D.; Vallier, T.L. 1994. The geologic evolution of the Pittsburgh Landing

area, Snake River Canyon, Oregon and Idaho. In: Vallier, T.L.; Brooks, H.C., eds.

Geology of the Blue Mountains region of Oregon, Idaho, and Washington: stratigraphy, physiography, and mineral resources of the Blue Mountains region. Professional Pap. 1439. Washington, DC: U.S. Department of the Interior, Geological

Survey; U.S. Government Printing Office: 55-73.

White, J.D.L.; White, D.L.; Vallier, T.L. [and others]. 1992. Middle Jurassic strata

link Wallowa, Olds Ferry, and Izee terranes in the accreted Blue Mountains island

arc, northeastern Oregon. Geology. 20: 729-732,

52
Section 3—Landscape-Level Ecoregions for

Seven Contiguous Watersheds, Northeast

Oregon and Southeast Washington

by Sharon E. Clarke, Mark W. Garner, Bruce A. Mclntosh, and James R.

Sedell1

Introduction Change is constant; streams have undergone millions of years of geological and

climatic processes; however, the rate of change of the present landscape is alarming.

Fifty years ago, spring chinook salmon (Oncorhynchus tshawytscha (Walbaum))

spawned in streams where they may never spawn again. Decreased ranges and declining numbers of other anadromous stocks and resident species also are evident.

The extent, complexity, and critical nature of this problem has been well documented

(Frissell 1993, Henjum and others 1994, Nehlsen and others 1991, Williams and

others 1989). Habitat destruction including loss of large pools, increased sedimentation, loss of complexity, decreased flows, and increased water temperature, is listed

as a major factor in this rapid decline (Frissell 1993, Henjum and others 1994,

Nehlsen and others 1991, Williams and others 1989). These stream habitat characteristics are influenced by instream and riparian zone processes as well as upland processes (FEMAT 1993, Frissell and others 1986, Gregory and others 1991, Henjum

and others 1994, Lotspeich and Platts 1982, Platts 1980) operating at many spatial

and temporal scales.

To recognize the role of upland processes in modifying stream habitat, we developed

landscape-level ecoregions (Level V). In the text, we use the term ecoregions as a

general term referring to ecological regions defined at any spatial scale; landscapelevel ecoregions refer to regions specifically delineated in this study, that is, an area

defined by specific landscape-level criteria to be smaller in scale than national-scale

ecoregions (Levels II and III) or a subregion (Level IV). Specific landscape-level criteria might be uniform soil, climate, topography, geology, geomorphology, or vegetation.

The spatial component of stream ecosystems was recognized by using a hierarchical

landscape stratification. The landscape stratification followed Warren’s (1979) ideas

of a classification system for watershed management adapted by Omernik (1987,

1995). Gallant and others (1989) described the process and uses of landscape stratification at the national and subregional scale. We used the concepts of hierarchical

stratification for aquatic organisms developed by Frissell and others (1986), Lotspeich

and Platts (1982), Minshall (1988), Platts (1980), and Warren (1979).

1

 BRUCE A. MCINTOSH is a stream ecologist, Department

of Forest Science, Oregon State University, Corvallis, OR

97331; and MARK W. GARNER was a GIS resource analyst

and JAMES R. SEDELL is a research ecologist, U.S.

Department of Agriculture, Forest Service, Pacific Northwest

Research Station, 3200 S.W. Jefferson Way, Corvallis, OR

97331.

53
Omernik and Griffith (1991) argue against the sole use of a hydrologic framework for

the study and organization of ecosystems. They state that, “although the longitudinal

linkages emphasized in the river continuum concept are important, we also must look

for important lateral linkages with regional characteristics.” Ecoregions account for

changes in stream habitat characteristics derived from changes in the surrounding

land, and watersheds account for the interconnectedness of water (Whittier and

others 1988). Combining landscape stratification with watershed delineations is appropriate for this study because the pathways for anadromous fish distribution are

determined by watershed linkages and landscape characteristics. To foster this union,

our study area was defined by watershed boundaries. For analysis, finer scale watershed delineations can be easily overlaid, with a GIS, on ecoregions by using a

“cookie cutter” approach. Landscape-level ecoregions form a bridge between finer

scale stream classifications and coarser scale ecoregions (Bryce and Clarke 1996).

The choice of which scale in the hierarchy to use depends on the question or management problem being addressed (Minshall 1988).

One of the cornerstones of Warren’s (1979) classification scheme is the idea of using

the potential capacity of the system. He suggests that “it is capacity of a system not

any particular performance, that most interests us. It is so because performances,

such as structure, of systems are in continuous flux and we want to know what we

can expect of a system.” He goes on to say the following:

We cannot have a system whose essential kind has changed placed in a different class every time its performance changes, as it will with environmental

change. It is useful to distinguish between the potential capacity of a system

and the different realized capacities it could come to have under different

developmental environments and at different stages in a given environmental

system through time.

He defines potential capacity “as all possible performances in all possible developmental environments.”

The ecoregion approach assumes that (1) streams are a reflection of the watersheds

that they drain and (2) ecoregions reflect the variability in the potential capacity of

streams. Climate, geomorphology, geology, topography, potential natural vegetation,

and soil influence substrate, water quantity and quality, habitat complexity, and riparian vegetation. The relative influence, or importance, of each differs from one region

to another. The grouping of areas having similar landscape characteristics allows a

better comparison of the potential capacities of streams of similar size between each

region.

Ecoregions have been developed at the national (Omernik 1987, 1995) and regionalstate level (Clarke and others 1991; Gallant and others 1989; Griffith and Omernik

1991; Griffith and others 1994a, 1994b; Thiele and others 1992) for research, resource management, and regulatory use. Landscape-level ecoregions are intended

to help address issues of research and management at a local scale by (1) anticipating the effects of different types and intensities of land uses, (2) providing a target

for restoring stream habitats, (3) selecting monitoring and research sites, and (4)

extrapolating data from research and monitoring sites to other streams with similar

potential capacity.

54
Watershed analysis uses maps of topography, stream networks, soils, vegetation, and

geology along with sequential aerial photographs, field inventories and surveys, census data on species presence and abundance, disturbance and land use history, and

other historical data to provide information on what processes are active within a

watershed, how these processes are distributed in time and space, what the current

upland and riparian conditions of the watershed are, and how all these factors influence riparian habitat and other beneficial uses. Landscape-level ecoregions combine most of the map types used in the watershed analysis and may provide a template on which to place the other types of information for a watershed. Specific monitoring objectives are derived during the watershed analysis process and are tailored

to each watershed. Riparian areas selected for monitoring are dispersed among the

various landscapes because of the influence of past disturbance, topography, climate,

and other factors on the natural conditions of stream habitat. Here too, we feel subregions or landscape-level ecoregions may provide guidance in selecting monitoring

sites.

Biologically based habitat standards—Rhodes and others (1994) set standards for

stream ecosystems based on available information about the biological-habitat requirements of salmon. They state that “meeting the habitat requirements of salmon

species must be the biological bottom line of efforts to protect and restore spawning

and rearing habitat consistent with efforts to stabilize and restore the listed salmon

runs.” No further degradation is allowed in stream systems that currently exceed the

biologically based habitat standards. Rhodes and others (1994) agree that classification is a useful tool for looking at questions of attainability of stream-habitat criteria

and channel response to perturbation. Using subregions or landscape-level

ecoregions may help fine-tune the habitat standards to reflect differences in the

potential capacity of streams. For example, biologically based habitat standards

should be the lowest acceptable standards, but for some systems, attaining these

standards still represents a degraded condition, and higher standards should be imposed. In other systems, natural conditions do not meet the biologically based habitat

standards. Efforts to meet the habitat standards in these streams may be unrealistic,

short term, and expensive. These efforts could detract from other more productive

efforts. Subregions or landscape-level ecoregions may be useful in identifying areas

where biologically based habitat standards are too low or difficult to achieve due to

the inherent potential capacity of the system.

River continuum—The river continuum concept (Vannote and others 1980) asserts

that stream ecosystems are connected and that conditions change accordingly from

headwaters to the mouth of a river. Because the differences created along a river

continuum are based on the landscape in which it is embedded, the idea of continuity

(the river continuum concept) needs to be merged with the idea of context (regional

classification). The effects of upstream and upslope regions and increasing stream

size need to be recognized in any interpretation of stream ecosystem research. Landscape classification provides a logical rationale for ordering and testing relations.

55
Stream-habitat classification—Landscape-level ecoregions were developed to complement stream-habitat classifications (Bryce and Clarke 1996). Stream-habitat classification is finer scale and focuses on the stream channel and valley floor. The merits

of stream-habitat classification are discussed by Bisson and others (1982), Cupp

(1988), Frissell and others (1986), Hawkins and others (1993), Lotspeich and Platts

(1982), Montgomery and Buffington (1993), Nawa and others (1991), and Rosgen

(1985). Stream-habitat classification coupled with a landscape classification of the

entire watershed recognizes the connectedness of the entire drainage network (Bryce

and Clarke 1996, Frissell and others 1986, Lotspeich and Platts 1982). In addition,

O’Neil and others (1986) suggest that using a hierarchical approach allows for patterns to emerge which may be masked at the next lower level in the hierarchy. Landscape-level ecoregions may identify patterns masked by the increased variability of

finer scale stream classifications. Although stream-habitat classification generally delineates the current state of the system, landscape-level classification aims to define

potential capacity. This difference makes interpretations and comparisons between

these two methods difficult.

Landscape-level ecoregions were developed to aid research and management of

anadromous fish and their habitat.3

 To provide a rationale for using a landscape

classification to understand fish distribution and abundance, we described the connections between landscape characteristics and stream-habitat characteristics and

between stream-habitat characteristics and fish distribution. The primary streamhabitat characteristics that influence fish distribution and abundance were substrate,

habitat complexity, riparian vegetation, water quality and quantity, and biota. Landscape characteristics, can directly or indirectly influence these stream-habitat characteristics. By identifying areas that are fairly homogenous in their mix of landscape

characteristics, we hypothesized that the potential capacity and the reaction to both

natural and anthropomorphic disturbances of streams will be influenced by the landscape characteristics that constitute landscape-level ecoregions.

Most of the literature discussing stream-habitat characteristics is focused on disturbed

conditions. We have used this information and related it to analogous natural conditions. In doing so, we recognized that a natural system has more resiliency than a

disturbed system.

Substrate—Topography, climate, vegetation, soil, and geology influence sediment

production and erosional processes (Swanson and others 1987). These landscape

characteristics influence the particle size and amount of sediment by affecting the

erosion, transport, and storage of soil particles. Table 3 shows the factors influencing

sediment production along with the relative risk to stream-habitat productivity.

3

 Principles used in defining the landscape-level ecoregions

for anadromous fish and their habitat may make them

applicable to other aquatic resource issues as well as some

terrestrial resource issues. An assessment of the usefulness

of the classification for other resources can be made by

evaluating the map and reading the rationale section.

Classes can be combined to meet the needs of other

resource projects.

Rationale for

Delineating

Landscape-Level

Ecoregions

56
Table 3—Factors that vary the risk of sedimentation limiting salmonid populations by habitat degradation3

Level of risk

Factor Decreasing ......................................................................................... Increasing

Climate Winter rain Summer rain, Spring Spring-fed

winter snow snowmelt

Erosive process Surface erosion Surface and mass Mass erosion

erosion, channel

erosion

Geology Metavolcanic, Sandstone, Granitic

volcanic siltstone

Topography Gentle terrain Moderate terrain Steep terrain

Stream gradient High (> 5%) Moderate (1-5%) Low (< 1%)

Channel morphology Narrow-deep Shallow-wide

Riparian vegetation Abundant Scarce

a Adapted from Everest and others (1987).

Surface erosion and mass movements contribute sediment to streams. Surface erosion involves detachment and movement of soil particles. Detachment is influenced

by soil texture and the amount of protection by vegetation. Precipitation intensity and

duration, soil infiltration rate, and slope gradient and length influence soil movement

(Swanson and others 1987, Swanston 1991). Where and when mass movements

occur, their size, and amount of material transported are controlled by slope, parent

material, depth and degree of weathering, and soil saturation (Swanston 1991). The

downstream movement and deposition of sediment are influenced by channel morphology, water quantity, and amount and size of material (Swanston 1991). Once the

sediment enters the stream, it may move as either suspended sediment or bedload,

depending on particle size and flow. Small headwater streams are usually more prone

to erosion because both the sideslope and channel gradient are steeper (Naiman and

others 1992). Interaction with the uplands also is greater for these small streams because there is a less-developed riparian buffer strip to act as a storage area for

sediments.

Erosion and sedimentation are natural processes that contribute to a healthy stream

ecosystem by providing the sources and surfaces necessary for aquatic habitat

(Naiman and others 1992). Both the particle size and amount of sediment in a stream

influence stream habitat. High concentrations of fine sediment may lead to overloading of substrate material (Heede and Rinne 1990). Fine sediment may directly

reduce the egg-to-fry survival and fry quality of anadromous salmonids by (1) decreasing water flow through the gravel of the redd therefore reducing dissolved oxygen and causing suffocation of eggs and alevin and (2) creating a physical barrier to

57
emergence (Bjornn and Reiser 1991, Everest and others 1987, Murphy and Meehan

1991, Petersen and others 1992, Rhodes and others 1994, Swanston 1991). Rhodes

and others (1994) report that decreased interstitial space from sedimentation results

in the elimination of fry from habitat, alters the food base, and reduces available winter interstitial habitat and consequently may increase presmolt mortality.

Indirect effects of sedimentation on salmonids include changes in channel morphology, increased turbidity, and decreased food availability (Everest and others 1987,

Murphy and Meehan 1991, Petersen and others 1992, Swanston 1991). An abundance of coarse-grained sediments may increase infiltration and percolation, thereby

reducing surface flows during dry conditions (Everest and others 1987). Different

salmonid species require different gravel substrate sizes for spawning; large fish can

use larger substrate materials than can small fish (Bjornn and Reiser 1991). Gravelsized material in riffles provides the primary food-producing areas for fish (Heede and

Rinne 1990).

Habitat complexity—Bisson and others (1982) define habitat complexity as the distribution and abundance of habitat types. Lichatowich and others (1995) add that complexity includes connectivity throughout the salmonid’s range. They define connectivity

as the ability to migrate at the appropriate time between links in the habitat chain.

Habitat complexity is controlled by discharge, sediment load, bank characteristics, and

structural features such as large woody debris (LWD), bedrock, boulders, and sediment wedges (Murphy and Meehan 1991, Sullivan and others 1987, Swanston 1991).

The presence of these structural features is determined by local geology and active

hillslope-and-channel erosion processes (Sullivan and others 1987, Swanston 1991).

The LWD input differs considerably, depending on species of trees growing alongside

a stream, soil stability, valley form, climate, and lateral channel mobility (Bisson and

others 1987, Maser and Sedell 1994, Sedell and others 1988). Inputs may be either

frequent chronic inputs or intermittent, sizeable inputs (Maser and Sedell 1994) depending on slope, climate, soil, and bedrock type. Pool-forming agents are influenced

by gradient, vegetation, and geology. For example, in high gradient streams, pools

form around structural features; and in low gradient systems, most pools are found

in meander bends.

Habitat complexity enhances diversity of species and age classes and translates into

a more resilient ecosystem (Franklin 1992, Hawkins and others 1993, Sullivan and

others 1987, Vannote and others 1980). Successional patterns of fish assemblages

in streams are usually spatial rather than temporal. Specialization for temporal stages

of ecological succession are not observed (for example, pioneering species); periodic

disturbances such as drought or floods cause species to relocate (Marcot and others

1994, Margalef 1960). A complex channel provides the needed refuges for such relocation (Sedell and others 1990). Flood plains and other seasonally wetted areas

provide access for aquatic organisms to off-channel habitats during high flows

(Sullivan and others 1987). Anchored driftwood and standing vegetation provide

quiet water refuges during floods (Maser and Sedell 1994, Sedell and others 1988).

Lichatowich and others (1995) identify the distribution and quality of salmon habitats

in a watershed as one of the three elements important to the life history-habitat relation of individual stocks. Diversity in life history dampens the risk of extinction or reduced production in fluctuating environments (Lichatowich and others 1995).

58
Habitat complexity can be organized hierarchically. Gregory and others (1991) and

Frissell and others (1986) use the terms reach, channel unit (pool/riffle), and subunit (microhabitat) to describe the hierarchical levels. Habitat complexity is a function of diversity within and between levels. Gregory and others (1991) define reaches

as sequences of channel units with distinct hydraulic and geomorphic structures reflecting different processes of formation. They describe a reach by the type and

degree of local constraint imposed on the channel and valley floor. Constrained

reaches tend to have relatively straight, single channels; unconstrained reaches in

natural systems are characterized by complex commonly braided or meandering

channels and extensive flood plains. Low gradient, wide valley bottoms, LWD, and

poor drainage increase the occurrence of braided channels. In larger rivers where

LWD does not span the channel, debris accumulations along the bank cause

meander cutoffs and may create well-developed braided channels (Bisson and others

1987). A meandering stream provides diverse flows and increases the probability that

the spawning and rearing needs of different life history stages of fish will be met

(Heede and Rinne 1990).

At a finer scale, the mix of channel units (for example, pools, riffles, and glides) contributes to habitat complexity. Channel units are differentiated by water-surface slope,

width-to-depth ratio of the channel, and extent of turbulent, high-velocity flow (Gregory

and others 1991). Channel-unit complexity provides favorable water-quality conditions,

food supply, and resting and hiding habitat within swimming distance (Heede and

Rinne 1990). Pools provide a feeding area where little effort may be needed to hold

position against the current (Bisson and others 1987, Maser and Sedell 1994). Migrating adults and juvenile salmon are dependent on pools for shelter from predators

and refuge from low summer flows and high winter flows (Petersen and others 1992).

Deep pools provide various microhabitats that allow different species of fish and fish

of the same species but of different ages to coexist (Maser and Sedell 1994).

The amount and type of LWD plays an integral role in creating habitat complexity. Debris creates complex pool types such as dammed pools, plunge pools, lateral scour

pools, and backwater or eddy pools (Bisson and others 1987, Bisson and others

1992). Local reductions in stream flow caused by LWD provide foraging sites for fish

(Sedell and Beschta 1991). The LWD decreases the erosive effects of flood water,

including reinforcing meanders (Beschta 1991, Naiman and others 1992, Petersen

and others 1992). In addition, LWD alters the stream profile and reduces local

gradient (Franklin 1992, Swanston 1991).

Gregory and others (1991) define subunits as local hydraulic features created by

boulders, logs, or gravel bars at scales less than the active channel width. They

describe subunits as transitory features over annual hydrological cycles, changing

rapidly with rising or falling water levels. Subunit complexity is provided by structures

such as wood, boulders, and gravel bars. Diversity within subunits provides cover as

protection from predators, competitors, or variation in streamflow. Cover is provided

by LWD, overhanging vegetation, rubble, boulders, undercut banks, and water depth

(Sullivan and others 1987). Low-velocity areas downstream of boulders or other flow

obstructions constitute resting, feeding, and spawning habitat (Heede and Rinne

1990). Stored gravel behind debris may provide excellent spawning habitat

(Swanston 1991).

59
Water quantity—The amount, timing, intensity, and type of precipitation are influenced on a broad spatial scale by climatic processes, modified locally by topography

and vegetation. Precipitation can be either stored as snow or immediately discharged

into the stream as overland or subsurface flow. Infiltration rates, storage capacity, and

transmission rates are related to soil characteristics (Swanston 1991). The major factors controlling stream flow are channel gradient, watershed size, type and density of

vegetation cover, precipitation characteristics, topography, and soil-infiltration rates.

The amount and timing of stream flows affect fish populations and all physical stream

characteristics. Water quantity influences stream temperature, erosion processes,

weathering rates, hillslope and channel sediment transport and deposition, channel

morphology, current velocity, and riparian vegetation. The quantity and duration of

stream flows are important to migrating salmon (Bjornn and Reiser 1991) and for the

stability of spawning gravel (Petersen and others 1992).

Riparian vegetation—The occurrence and type of riparian vegetation are mainly controlled by channel geomorphology, the spatial position of the channel in the drainage

network, soil, and climate (for example, hydrologic regime) (Naiman and others 1992).

Riparian vegetation contributes terrestrial invertebrates to streams as a food source

for fish and organic matter as an energy base for stream biota (Beschta 1991,

Gregory and others 1987). The indirect role of riparian vegetation in providing fish

habitat is extensive. In summer, riparian vegetation provides shade to streams and

lowers summer temperatures; and in winter, riparian vegetation moderates thermal

temperature losses from streams and retards the formation of ice (Beschta 1991,

Franklin 1992). Riparian vegetation reduces flow velocities, which allows for deposition of sediments and contributes to the long-term accretion of alluvium on flood

plains (Beschta 1991). The root systems of riparian vegetation help to stabilize the

banks during high flows (Beschta 1991, Franklin 1992, Sedell and Beschta 1991).

Riparian vegetation is the main source for LWD, contributing to habitat complexity by

affecting the dissipation of stream energy and creating local channel scour and deposition (Beschta 1991). Riparian vegetation slows the flow of water, allowing it time

to infiltrate into the bank. This infiltration helps to decrease peak flows, maintain local

water tables, and extend base flows through summer (Wissmar and Swanson 1990).

Biota—The important biotic components of salmonid habitat are interspecies and

intraspecies interaction and food sources. Species interactions are largely a function

of the other physical components that have been discussed, such as habitat complexity. Salmonids are opportunistic feeders that eat aquatic and terrestrial invertebrates. Food abundance along with physical habitat and salmonid behavior interact

to determine the carrying capacity of a stream (Murphy and Meehan 1991). The relative importance of food is seasonally dependent. Food is more important in summer

than cover, and in winter the opposite is true, although exceptions are many (Murphy

and Meehan 1991).

Current velocity, temperature, substrate, vegetation, and dissolved substances influence the abundance and distribution of aquatic invertebrates. Of lesser importance

are susceptibility to drought and floods, species competition, shade and zoogeography (Hynes 1972). These factors are influenced by landscape characteristics.

60
Energy for food is available to a stream from two types of sources: autochthonous

(photosynthesis within the stream) and allochthonous (decomposition of terrestrial

organic matter) (Murphy and Meehan 1991). The three basic autochthonous forms

are phytoplankton, periphyton, and vascular macrophytes. Each form characterizes

streams of different sizes, gradient, and exposure to sunlight. The five main allochthonous inputs are (1) streamside litterfall, (2) ground-water seepage, (3) soil erosion, (4)

fluvial transport from upstream, and (5) animal activities (Murphy and Meehan 1991).

Movement of organic matter depends on stream flow, particle size, and retentive

capacity of the channel.

Water quality—In natural streams there is a wide variability in water quality due to

the large number of controlling factors. Fish production can be altered by activities

that affect water quality and quantity or regimen (Meehan 1991). Naiman and others

(1992) focused on five elements of water quality in the Pacific Northwest Coastal

ecoregion; nitrogen, phosphorus, turbidity, temperature, and intragravel dissolved

oxygen (DO). Landscape factors are important in controlling water quality in Pacific

Northwest Coastal ecoregion streams (table 4).

Both nitrogen and phosphorus are important elements in the food chain (Naiman and

others 1992). Turbidity, usually caused by suspended silt and clay particles, has wideranging effects on salmonids, invertebrates, and other aquatic organisms. Intragravel

DO is reduced by turbidity and sedimentation and is critical for salmonid reproduction, invertebrates, and other aquatic life.

Seasonal and diel stream temperature influences (1) trophic structure and composition; (2) habitat selection; and (3) fish metabolism, development, and activity (Beschta

and others 1987). The influence of temperature on habitat selection was demonstrated in Oregon by Bond and others (1988) who found that when looking at summer

stream temperature, significantly distinct habitat-use patterns appeared for 17 of the

25 native species analyzed. Stream temperature is important for bull trout; they require very cold water for most of their life history. Henjum and others (1994) report

that published temperature tolerances for bull trout are much lower than for other salmonids for spawning 4 to 10 °C (39 to 50 °F) and egg incubation 1 to 6 °C (34 to 43

°F). Effects of higher stream temperature can be both positive and negative, although

the positive effects have only been indicated at the reach level in fairly cold systems.4

Warm temperatures (1) increase the potential for competition with warm water species, (2) reduce rearing-area availability, and (3) increase susceptibility to disease

(Henjum and others 1994, Rhodes and others 1994). For example, increased exposure to sunlight can stimulate algal growth which may provide more food for fish;

but if the temperature exceeds the range of efficient metabolism, growth rates are

reduced (Petersen and others 1992).

Stream temperature also may impact substrate, indirectly. Stream temperature is

inversely related to water viscosity. Cooler, denser water can hold more sediment in

transport and may reduce the fine-sediment loading of gravel used for spawning

(Heede and Rinne 1990).

4 Personal communication. 1995. J.J. Rhodes, hydrologist,

Columbia River Inter-Tribal Fish Commission, 729 N.E.

Oregon, Suite 200, Portland, OR 97232.

61
Table 4—Relative importance of landscape factors controlling water-quality

elements in the Pacific Northwest Coastal ecoregion3

Water-quality element

Controlling Intragravel

factor Nitrogen Phosphorus Turbidity Temperature DO

Climatic and

atmospheric

inputs H L M H L

Geology and

soil M H H M H

Stream order M M M H M

Constrained

or

Unconstrained H H H M M

Vegetation H M M M L

a From Naiman and others (1992); importance is coded as H-high, M-medium, and L-low.

Beschta and others (1987) describe the interaction between landscape characteristics

and stream temperature. The routing of water flow (surface versus subsurface) impacts the temperature of water entering a channel. Subsurface flow reflects the temperature of the subsoil environment of the watershed. In the stream, water temperature changes because of net radiation, evaporation, convection, conduction, and advection. Net radiation is the solar radiation absorbed by a stream surface. This is affected by topographic and vegetative shading and cloud cover. Albedo of the stream

also may influence net radiation; a clear stream is a black body, and a turbid stream

reflects solar radiation.5

Heat gain or loss from evaporation depends on the vapor pressure gradient between

the water surface and the air immediately above the surface. Convection, internal

movement within a fluid because of differences in density or temperature, increases

with increase in temperature gradient between the water surface and the air immediately above the surface. Wind speed at the air-water interface is also an important

factor. Conduction of heat between the water in the stream and the streambed depends on the type and color of material that makes up the bed. A dark basalt absorbs

more heat than a light granite. Bedrock channels are more efficient than gravelbed

channels at conducting heat.

5 Logan, H.; Lammers, D. [1966]. Turbidity of upper Gallatin

River determined from IR photographs. Unpublished report.

On file with: U.S. Department of Agriculture, Forest Service,

Gallatin National Forest, Federal Building, 10 E. Babcock

Avenue, Box 130, Bozeman, MT 59771.

62
The importance of ground water to salmonids also is being recognized. Advection is

the result of heat exchanges as tributaries or ground water of different temperature

mixes with the main streamflow. Areas of upwelling ground water and aggraded flood

plains were historically key production areas for salmon. Bedrock outcrops and encroaching canyon walls are often locations for ground-water discharge (Stanford and

Ward 1992). Springs also may provide important cool water refugia (Bilby 1984).

Channel characteristics and morphology also influence the amount of heat gain or

loss of a stream. The surface area over which energy transfers take place is important; wide, shallow streams receive more solar energy than do narrow, deep ones.

Discharge also is significant in that for the same surface area and energy input, the

temperature change expected of a high-discharge stream will be less than that of a

low-discharge stream.

Delineation of Data sources—The study area includes the Grande Ronde, Asotin, Tucannon,

Landscape-Level Imnaha, Walla Walla, Umatilla, Middle Fork, and North Fork John Day subbasins

Ecoregions and the upper reaches of the mainstem John Day subbasin (fig. 3). Primary types of

mapped information used to delineate landscape-level ecoregions were soil, historical

and present-day vegetation, geology, topography, and climate. Because the quality

of the landscape-level ecoregion map is partly a reflection of the quality of the source

material, a detailed description of each source along with an assessment of its quality

and its utility to the delineation process is provided in the discussion of each landscape characteristic. Table 5 summarizes the source maps used in the delineation

process.

Data integration—Ecoregion lines were drawn by using a synthesis of digital layers,

maps, and descriptive information. We used topographic maps as a base because

(1) frequently the other landscape characteristics follow topography and (2) these

 maps are readily available and meet national map accuracy standards (USDI Geological Survey 1989). A GIS was useful for easily combining map units into groups

that we felt were important for stream habitat and plotting maps at our working scale

of 1:100,000. For each available digital layer, 1:100,000-scale color plots were made

to overlay the 1:100,000-scale topographic quadrangles. Lines from each plot were

color-coded by landscape characteristic and transferred to clear Mylar. Each topographic quadrangle had a Mylar sheet for vegetation, geology, and soil. A blank sheet

of Mylar was used to sketch ecoregion lines.

Topographic maps along with the Mylar overlays of soil, geology, and vegetation were

overlain singly and in combinations on a light table. Placement of ecoregion lines was

based on knowledge of how landscape characteristics might influence stream habitat.

Location of landscape characteristics on nondigital maps of differing scales and

written descriptions were visually estimated, and this information also was used in the

delineation process. Greater emphasis was placed on maps of higher quality and

better resolution. Lines were not determined by overlaying source maps within a GIS

because of (1) lack of necessary information in GIS format; (2) differences in quality,

scale, and resolution of the source maps; (3) use of nondigital maps; (4) use of descriptive information; (5) spatial differences in importance of the properties of each of

the landscape characteristics; and (6) differences in importance of each of the landscape properties in influencing stream habitat. Further discussion of the method can

be found in Bryce and Clarke (1996), Clarke and others (1991), Gallant and others

(1989), and Omernik (1987, 1995).

63
Seven contiguous watersheds in

N.E. Oregon and S.E. Washington

Figure 3—Study area watersheds.

After delineating approximate boundaries for landscape-level ecoregions from all

available map and textual sources, we evaluated the boundaries. The first set of draft

lines were transferred to a plastic-coated 1:100,000-scale topographic map for use in

the field. About 3 weeks of road surveys were conducted to evaluate the lines and

questionable areas. Slides and a video were obtained for later use in the lab. In addition, local biologists, geologists, and soil scientists were contacted to assist in making

boundary determinations in specific areas.

Map production—As a result of this field evaluation, some lines were redefined on

the original Mylar copy, and all lines were digitized into an ARC/INFO coverage. After

digitizing, plots were made for each of the 1:100,000-scale topographic maps. Lines

were reassessed by comparing them to the individual maps of landscape characteristics and checked for accuracy of labels and line digitizing. As a result of this step,

changes were made to the digital map.

A map of landscape-level ecoregions was produced for seven contiguous watersheds within the Blue Mountains and Columbia Plateau ecoregions (insert C). The

map depicted three levels in the ecoregion hierarchy—ecoregions, subregions, and

landscape-level ecoregions.

64
Table 5—Source maps used to delineate landscape-level ecoregions

Minimum

Landscape mapping

characteristic Scale Subject Source Date GIS unit

Topography 1:250,000 Digital elevation USDI GS 1987 1970- Y 60 x 90 m

models (DEM) 1981 (66-98

yd) grid

1:100,000 Topographic maps USDI GS 1979- N

1982

Soil 1:250,000 STATSGO (OR and WA) Soil Conservation Service 1993 Y 625 ha

(1,544ac)

1:63,360 National Forest soil Carlson (Malheur) 1974 N

resource inventories Paulson (Ochoco) 1977 N 20 ha

(50 ac)

Ehmer (Umatilla) N.y. N

Wallowa-Whitman NFa 1993 Y

1:20,000- County soil surveys Soil Conservation 1962- N 2 ha (5 ac)

1:31,680 Servicebc 1991

Climate 1:500,000 Normal annual Taylor (OSU) 1994 Y 8 km (4.97

precipitation mi) grid

1:2,000,000 Precipitation map (WA) Miller (NOAA) 1973 Y

Digital WADNR

1:250,000 Rain-on-snow zones (WA) Brunengo (WADNR) 1991 Y

Geology 1:500,000 Geology (OR) Walker and MacLeod 1991 Y

(USDI GS)

1:250,000 Geology (SEWA) Johnson and Derkey 1993 Y

(USDI GS)d

1:24,000 Granite Quad Brooks and others 1982 N

(OR) (USDI GS)

1:250,000 Canyon City Quad (OR) Brown and Thayer 1966 N

(USDI GS)

1:62,500 Desolation Butte Quad Evans (USDI GS) 1989 N

(OR)

1:24,000 Limber Jim Quad (OR) Ferns and Taubenack 1994 N

(USDI GS)

1:100,000 Connell Quad (WA) Gulick (WADNR) 1994 N

1:100,000 Puliman Quad (WA) Gulick (WADNR) 1994 N

1:125,000 John Day Formation (OR) Robinson 1975 N

1:100,000 Clarkston Quad (WA) Schuster (WADNR) 1993 N

65
Table 5—Source maps used to delineate landscape-level ecoregions (continued)

Minimum

Landscape mapping

characteristic Scale Subject Source Date GIS unit

1:100,000 Walla Walla Quad (WA) Schuster (WADNR) 1994 N

1:250,000 Pendleton Quad (OR and Walker (USDI GS) 1973 N

WA)

1:250,000 Grangeville Quad Walker (USDI GS) 1979 N

(OR and WA)

1:250,000 Columbia River Basalt USDI GS 1980 N

Group (WA and ID)

1:100,000 Lignite and coal resources Ferns 1985 N

(NE OR) DOGAMI)

1:250,000 Umatilla Indian Res. (OR) Gonthier and Bolke 1993 N

(USDI GS)

1:62,500 Upper Grande Ronde River Hampton and Brown 1964 N

basin (OR) (USDI GS)

1:127,000 Umatilla River basin (OR) Hogenson (USDI GS) 1964 N

(approx.)

1:95,000 Walla Walla River basin Newcomb (USDI GS) 1965 N

(approx.) (OR and WA)

Vegetation 1:63,360 Forest type class. USDA FS 1935- Y

(OR and WA) 1960

1:253,000 Forest type map (OR) USDA FS 1936 N

(approx.)

1:253,000 Forest type map (WA) USDA FS 1936 N

(approx.)

1:250,000 Actual vegetation (OR) Kagan and Caicco 1992 Y 133 ha

(U of ID) (328 ac)

a

 Wallowa-Whitman National Forest (Art Kreger). 1993. Digital soil survey, dated 1993 to Sharon Clarke. On file with: Wallowa-Whitman

National Forest, Baker City, Oregon.

b Dyksterhuis 1981; Dyksterhuis and High 1985; Gentry 1991; Harrison and others 1962, 1973; Hosier 1983; Johnson and Makinson 1988;

NRCS 1995; unavailable—Wheeler County, Oregon.

c U.S. Department of Agriculture, National Resources Conservation Service (formerly, Soil Conservation Service). 1995. Wallowa County soil

survey. [Place of publication unknown]: [Publisher unknown].

d

 Johnson, B.R.; Derkey, P.O. 1993. Geologic map compilation of southeast Washington. Digital data. Draft dated 1993 to Sharon Clarke. On

file with: U.S. Geological Survey, Spokane, Washington.

66
Each landscape-level ecoregion differed from the adjoining region in one or more of

four landscape characteristics: topography, soil, vegetation, or geology. A short, descriptive name was developed for each landscape-level ecoregion based on the defining landscape characteristics. Every map unit was color-coded and given a label

corresponding to the name in the legend. For example, “pag” refers to a unit named

ponderosa pine argillite. Our smallest map unit was 0.5 square kilometer (0.2 mi 2

),

and because landscape-level ecoregions were sometimes discontinuous, the smallest

landscape-level ecoregion was 2.6 square kilometers (1 mi2

). In describing each of

the landscape characteristics, this label identifies the map unit associated with that

characteristic. For example, when describing the areas of argillite, the map units containing “ag” may be either “pag” or “tag”; ponderosa pine argillite or true fir argillite,

respectively. Usually a landscape-level ecoregion occurred within one subregion; but

in specific cases, it may have occurred within additional subregions as well. For example, most of the regions comprised of true fir forests are located within the Mesic

Forest subregion. Small disjunct patches of true fir occur, however, in lower elevation

subregions. These areas were too small to be mapped as subregions but were large

enough to be defined at the landscape-level ecoregion scale.

Landscape characteristics—Individual landscape characteristics rarely (or perhaps

never) independently influence stream habitat, although dominance may vary spatially. The type and magnitude of influence also vary spatially. This spatial diversity

of influence is why we defined ecoregions by multiple landscape characteristics. The

prediction of stream-habitat characteristics based on the stream location within an

ecoregion is impossible for several reasons, however. First, we lack the scientific

knowledge to relate an individual landscape characteristic type directly to a particular

stream habitat characteristic. Also, landscape characteristics generally are mapped

as discrete units, although in reality they occur as a continuum. Individual properties

may combine to moderate or increase an effect, usually not in a direct 1:1 relation.

Finally the characteristics of the land adjacent to the stream, in concert with upslope

characteristics and upstream influences, work to determine the characteristics of the

stream.

We make no pretense that by using landscape-level ecoregions, we can somehow

predict the stream-habitat characteristics of an individual stream within any delineated landscape-level ecoregion. Stream-habitat characteristics, however, are influenced by landscape characteristics, and landscape-level ecoregions are delineated

by using landscape characteristics; so it follows that stream-habitat characteristics

may be related to landscape-level ecoregions. To elucidate the connection between

landscape-level ecoregions and stream habitat, the relations between each of the

landscape characteristics and stream habitat are discussed. Discussion of geologygeomorphology and vegetation is by individual types and discussion of climate and

soil is by properties.

Climate—Climate is predominantly influenced by elevation, aspect, availability of

moisture, and the prevailing wind direction. In turn, climate greatly influences vegetation, soil-forming processes, and geomorphology. Every aspect of stream habitat is

directly or indirectly affected by climate.

67
Climate is an important landscape characteristic; however, developing meaningful

classes for climate is difficult. As Daubenmire (1956) found out when trying to use

climate classifications to explain patterns of vegetation, “the major finding of the

study, [was that] none of the four universal classifications of climate tested has much

phytogeographical significance in the area under consideration [eastern Washington

and northern Idaho].” He suggested that because vegetation, soil, and climate are

correlated in this area, they should be used to recognize the same landscape units.

Because annual means of temperature and precipitation mask information on daily

and monthly variability that is important to understanding vegetation patterns and

erosional processes, the few maps of annual precipitation that were available for the

study area did not weigh heavily in our delineation process. As Daubenmire (1956)

points out, “Ecologists have for some time been aware that annual means of tempera

ture (and to a certain extent, precipitation also) are scarcely worth even the small

amount of trouble involved in their calculation “

For Oregon, an annual precipitation map developed by the Oregon Climate Service

using PRISM (Precipitation-Elevation Regressions on Independent Slopes Model) was

available. This model attempts to correct for the lack of weather stations in mountainous areas (Taylor 1994). PRISM uses precipitation data collected from weather

stations and a digital elevation model (DEM) to generate estimates of annual precipitation. Precipitation data came from two primary sources, National Climatic Data

Center (NCDC) cooperative stations and Natural Resource Conservation Service

(NRCS) snow telemetry stations for the period 1961 to 1990. Two terrain grids were

used with 2.5- and 5-minute latitude-longitude terrain elevations. The 5-minute grid

(about 6 by 8 km per grid cell) was better able to resolve orographic effects (Taylor

1994).

For Washington, we used several maps from the State of Washington, Department

of Natural Resources. A very coarse-scale precipitation map (Miller and others

1973) was marginally useful; more useful was a map showing rain-on-snow zones

(Brunengo 1991). These zones generally corresponded to elevation.

Climate more than any other factor controls the rate and nature of weathering of parent material. In arid areas, physical forces dominate weathering, decreasing the size

of particles with relatively little change in composition (Brady 1990). Precipitation increases with elevation and changes physical form while temperature decreases. A

snow-dominated area is more likely to experience flooding because of either an early

spring thaw or a rain-on-snow event. Increased precipitation directly affects the water

quantity. Water is the primary mechanism for transporting substances within and from

forested lands (Gill 1994). Erosion may be increased by higher precipitation, runoff, or

stream discharge. The erosional effects of higher precipitation may be mitigated by increased vegetation and concurrent increased infiltration and storage capacity of soils.

Topography has a major influence on climate in this area. The Rocky Mountains block

this region from the continental air masses moving from the east (Franklin and

Dryness 1988), and the Cascade Range partially block the maritime influence of the

Pacific Ocean. Precipitation falls mainly in winter, although local thunderstorms are

common in summer. Most of the winter precipitation falls as snow in the higher elevations. Rain-on-snow is common in the lower elevations. Summers are dry and hot,

and the winters are comparatively mild for this latitude, although not as mild as winters west of the Cascade Range. Climate in the Blue Mountains is noticeably different

from the climate in the Columbia Plateau.

68
The Columbia Plateau is dry; precipitation increases as elevation increases. In the

western part of the Columbia Plateau, this precipitation pattern forms a roughly concentric circle (Franklin and Dryness 1988). The lowest elevations, closest to the

Columbia River receive about 10 to 23 centimeters (4 to 9 in) per year, increasing up

to 40 to 60 centimeters (16 to 24 in) in the foothills of the Blue Mountains. Prevailing

winds are from the west or southwest, which causes the western slopes of the Columbia Plateau to be influenced by the maritime air funneling through the Columbia

River Gorge. Eastern slopes are drier because they are in the rain shadow formed

by the Blue Mountains (Gentry 1991).

The diverse topography in the Blue Mountains influences local climate (Johnson and

Clausnitzer 1992). Generally cooler temperatures are found as elevation increases.

Many valleys, however, are colder than the lower slopes of the adjacent mountains

because of cold air drainage. The maritime-influenced areas of the Blue Mountains

have greater cloudiness, increased precipitation, higher relative humidity, and fewer

fluctuations in winter temperature than the nonmaritime-influenced areas (Johnson

and Clausnitzer 1992). Most of the Blue Mountains, except for the John Day basin,

are influenced somewhat by the maritime climate.

The John Day basin is influenced less by the maritime climate and is in the rain shadow formed by the Cascade Range. Light precipitation, low relative humidity, rapid

evaporation, abundant sunshine, and wide temperature and precipitation fluctuations

characterize this region (Johnson and Clausnitzer 1992). Here the temperature in the

winter is much colder, and precipitation ranges from 25 to 51 centimeters (10 to 20

in) in the grasslands to 43 to 76 centimeters (17 to 30 in) in the higher forested elevations (Dyksterhuis 1981).

Soil—The importance of soil characteristics to stream habitat is not completely reflected in the mapping of landscape-level ecoregions. At the time of the mapping,

readily useable soil information was lacking.

The STATSGO coverages were obtained from the USDA Soil Conservation Service

(SCS)6

 for Oregon and Washington (USDA 1993). This digital map and database

were compiled from detailed soil survey maps and data on geology, topography, vegetation, climate, and Landsat images. On a STATSGO map, each map unit contains

up to 21 components for which there are attribute data, but there is no visible distinction as to the geographic location of these separate components within the map unit.

However, the percentage of each component is given, which was useful for our project. For each component, we looked at drainage, surface texture, permeability, and

depth to bedrock. Within each component, data are provided for each soil layer. We

looked at erodibility, percentage of clay and organic matter, and layer depth for the

top layer of each component. With this information, we derived a rough assessment

of each map unit.

6

 Soil Conservation Service became the U.S. Department of

Agriculture’s National Resources Conservation Service in

late 1994

69
The STATSGO data were too general for this project, and county and forest soil surveys were too detailed. If the county and forest surveys had been compatible and

available digitally, we could have reclassified the data and made them more useful

for our project. The lack of digital versions with an accompanying database was problematic; besides not allowing for reclassification, maps could not be produced at our

working scale of 1:100,000. We located soil polygons by using many individual map

sheets, usually bound in a book, with descriptive information located on other pages.

This was an error-prone and laborious method that was used mainly in the lower

elevation agricultural areas, where soils played a more dominant role and there were

questions raised from the other data sources.

The National Forest Soil Resource Inventories (SRI) delineate soils on high-elevation

aerial photographs. For our purposes, the maps are too detailed. Each National Forest has one or more SRI books with maps and soil descriptions. For each map, unit

information is provided on plant community types, physiographic position, geologic

materials, aspect, slope, present erosion, major drainage dissection, ground cover,

overstory and understory vegetation, rock outcrops, estimated water holding capacity,

erosion, and hydrology.

County soil surveys delineate soil phases, which are generally subdivisions of a soil

series based on surface layer texture or slope. A soil series is defined as a group of

soils having horizons similar in differentiating characteristics and arrangements in the

soil profile (Soil Conservation Society of America 1982). Each soil phase is described

in the county soil survey. From these descriptions, we obtained information on depth

to bedrock, drainage, parent material, topographic position, potential natural vegetation communities, land use, and ranges for precipitation, air temperature, slope, and

elevation. These maps also used aerial photographs as a mapping base. Most of

these photos have not been rectified, which made input into a GIS a major task.

Although the science of soil classification is fairly sophisticated, the hierarchical

scheme was difficult to use. We found the most useful level of information was the

soii series. Using soil series has several drawbacks, however: (1) the USDA Forest

Service’s SRI do not use the soil series names; (2) individual landscape-level

ecoregions were frequently comprised of several to many soil series; (3) soil series

names are not common knowledge, (for example, Athena soils would not convey

deep loess soils to most people unless familiar with the soils of the area); and (4)

some of the soil characteristics important to stream habitat (that is, texture and slope)

may not be reflected until the next lower level in the soil classification hierarchy, the

soil phase. By using soil descriptions, however, much useful information can be

learned that may influence stream habitat.

Ideally, we would like to have uniform digital coverage of soils at a scale of 1:100,000

or finer with an accompanying database reflecting soil characteristics for each

polygon. This type of soil data would have allowed us to aggregate polygons on the

basis of the characteristics we felt were most important in influencing stream-habitat

characteristics. Both the NRCS and the USDA Forest Service are heading in this

direction. In addition to being difficult to work with, the available information is difficult

to discuss in terms of importance of the different soil classes to stream habitat.

70
Table 6—Principal soil series names for map units defined primarily by soil characteristicsa

 (continued)

Soil series

Map unit Description Dominant subregion(s)b names

glomd/h Grassland moderately deep loess 10c Gwin

on hills Waha

Rockly

Gurdane

glos/h Grassland shallow loess on hills 10c Gwin

Gurdane

Rockly

glodx/h Grassland deep, xeric loess on 10c Walla Walla

hills 10b Scabland Loess

Islands

gbs/h Grassland biscuit scabland on 10c Morrow hills

Bakeoven

Condon

gloal Grassland deep loess and old 10c Pilot Rock

alluvium McKay

ges Grassland eolian sands 10e Pleistocene Lake Quincy

Basins Sagehill

Hezel

ggfg Grassland glaciofluviate gravel 10e Quincy

deposits Hezel

ggfs Grassland glaciofluviate sand and 10e Ellisforde silt

deposits Sagemoor

ggo/t Grassland aridic glacial outwash 10e Farrell

on terraces Roloff

gaca Grassland aridic loess over 10e Shano

cemented alluvium Burke

gloda/h Grassland deep, aridic loess on 10b Scabland Loess Ritzville

hills Islands Ellisforde

a

 Soil series names from STATSGO and county soil surveys.

b

 See insert B.

71
Table 7—Properties for ash-, sandstone-, and basalt-derived soila

Properties

Soil Bulk Coarse

fragments density Porosity Clay fragment Available water

Mg/mm3 Percent volume Percent weight Percent volume Percent volume

Ash 0.6-0.7 73-77 3-10 0-4 26-30

Basalt .9 65 20 30 13

Sandstone 1.6 40 10 0 14

a

 Adapted from Harvey and others (1994).

Table 8—Characteristics of soils by texturea

Soil texture Porosity Permeability

Percent Meters/day

Clay 45-60 0.00001-0.001

Silt 20-50 0.01-10

Sand 30-40 10-100,000

Gravel 25-40 1,000-10,000,000

a

 From Gregory and Walling (1973).

72
Johnson and Clausnitzer (1992) classify soils in the Blue and Ochoco Mountains in

the following broad categories: (1) residual-derived in place from predominately bedrock or colluvial rock materials; (2) ash/loess-derived from deposited and accumulated

ash and loess over older buried soil material; and (3) mixed-derived from colluvium,

ash, and loess mixed well in surface layers over buried soil material. Residual soil

differs from volcanic ash and loessial soil in several respects; it has (1) finer texture

in the upper profile, (2) increased structure, (3) higher amounts of coarse fragments,

(4) lower water-holding capacity, and (5) greater bulk densities. Ash soils have (1)

high water-holding capacity, (2) high water-infiltration rates, (3) low compactability, (4)

little particle cohesiveness, and (5) disproportionately high amounts of nutrients in

upper surface layers. Loessial soil (1) is normally high in base saturation (can hold a

large amount of nutrients), (2) has high content of weathered minerals and is thus

high in nutrient reserve, and (3) generally has excellent physical properties. Productivity of plant communities is closely related to the ash and loess content of the soil.

Hall (1973a) tabulated the stocking in trees per hectare (trees per acre) at 15.2 centimeters (6 in) average diameter at breast height (d.b.h.) with 25.4 rings per centimeter

(10 rings per in) growth for mixed conifer with residual soil to be 111 to 134 (275 to

330) versus 138 to 160 (340 to 395) for mixed conifer with ash soil. Because southern and southwesterly slopes were exposed to the prevailing wind in the Blue Mountains, the deposits of loess were shallower. Also, the loess came from the north, so

the south-facing slopes were sheltered from the deposits. Under some conditions, ash

soils support good vegetation cover that protects the ash from erosion (Johnson and

Clausnitzer 1992). The development of soil in the thick ash deposits of the John Day

Formation, however, was hampered by lack of moisture. Lack of soil development

and moisture increased erodibility and hampered vegetative cover. Lack of vegetation in turn contributed to increased erosion and lack of soil development. Lack of

moisture seems to be the key factor in this positive feedback.

Vegetation—Vegetation is the most dynamic of all the landscape characteristics used

to define landscape-level ecoregions. Johnson and others (1994) state that “the vegetation of east-side Washington and Oregon has a long history of natural disturbance.” Fire, grazing and browsing by ungulates, insect outbreaks, disease epidemics,

windthrow, flooding, and erosion have enhanced biodiversity. Management-induced

disturbances have modified the natural order in ways both complementary and detrimental to east-side ecosystems (Johnson and others 1994).

Because vegetation is dynamically influenced by both natural and anthropomorphic

disturbances, vegetation classifications and maps differ widely. An assessment of the

advantages and limitations of the existing vegetation classifications and maps to the

goal of the project was essential. The goal of this project was to define landscapelevel ecoregions as a tool to better understand the potential capacity of streams. To

use the best available information, we kept in mind the characteristics of vegetation

that may influence a stream’s potential capacity. Ideally, we were interested in obtaining a classification of vegetation that factored in the role of natural disturbance,

while acknowledging that it was extremely difficult or perhaps impossible to tease

apart natural from anthropomorphic disturbance, especially with the issues of fire and

grazing.

73
Table 9—Stocking per hectare (acre) in trees at 15.2 centimeters (6 in) average diameter at breast heighta

Tree Number stocked

Ponderosa pine/grassland 25-96 (63-238)

Ponderosa pine 85-168(214-415)

True fir 115-251 (285-620)

Subalpine fir 99-194 (245-480)

a

 25 rings per centimeter of growth (10 rings per inch of growth). From Hall (1973a).

Vegetation directly influences stream habitat by providing shade and LWD and other

organic matter to the stream. Vegetation influences erodibility, which in turn influences

substrate and habitat complexity. Vegetation also serves as a climatic indicator, providing valuable clues to moisture and temperature regimes (Woodward 1987). The

amount and importance of precipitation, interception, transpiration, infiltration, and

runoff differs considerably among forest types (Gill 1994). Differences in soil, climate,

and vegetation density all contribute to this variation.

There is a general trend to increased tree stocking with increased elevation, peaking

with the true fir. Hall (1973a) has recorded tree stocking ranges in the Blue Mountains (table 9).

The ponderosa pine-grassland areas have the lowest stocking, and the true fir has

the highest, although the range is quite variable. The vegetation density of an area

affects sensitivity to erosion, stream temperature, and snow melt. For western forests,

Franklin (1992) found that old-growth forests intercept a large portion of the snow.

The intercepted snow either melts and drips to the ground or is lost to sublimation

and evaporation. In cutover lands, deeper accumulations of snow occur, and melting

occurs more rapidly because wind speed and turbulence at the snow surface are

higher. We speculated that the same principle may hold true for closed-canopy versus

more open-canopy forests, although snow depth would be less for the lower elevation

forests.

Soil organic matter plays a role in soil-water availability, nutrient cycling, and erosion

control (Harvey and others 1994). In lower elevation vegetation zones, the nutrientrich surface layer is usually washed away. Lower site productivity from reduced nutrients coupled with a drier moisture regime results in a lower soil organic content. Generally, soil organic content is highest in the moister zone of true fir and lower in the

drier zone of ponderosa pine. Buckhouse and Gaither (1982) found in a study of sediment losses from 10 natural ecosystems that meadow and forested ecosystems were

statistically similar and that losses for grassland, sagebrush, and juniper were significantly higher than the meadow and forested ecosystem.

74
The vegetation information used to define landscape-level ecoregions was a synthesis of available information. Each piece of information had its utility and its limitations.

The concept of potential natural vegetation (PNV) was the most useful for this project,

attempting to map vegetation as it might appear if humans were removed from the

landscape. The only available PNV map of the area, however, was Kuchler’s map of

the United States at 1:7,500,000 scale (USDI Geological Survey 1970), which was

too general for our purpose.

The concept of plant associations was theoretically useful. If a stand of vegetation is

able to develop and persist in its environment, and if the competitive forces are without major disturbing influences, then following a relatively long period, those plants

capable of reproducing in competition will constitute the “climax community.” The unit

of classification based on the probable, or projected, climax community type is defined as the “plant association” (Johnson and Clausnitzer 1992). Hall (1973a, 1973b),

Johnson and Clausnitzer (1992), and Johnson and Simon (1987) have produced

thorough handbooks on the plant associations of the Blue Mountains. Their descriptions of plant associations were informative and provided some information useful in

making boundary decisions. However, very small-scale dot maps frequently were the

only spatial information found in plant association reports. These dot maps gave approximate locations where certain plant associations were found. This type of mapping was inadequate for our purposes. In addition, much of the work in forested communities (Hall 1973a, 1973b; Johnson and Clausnitzer 1992; Johnson and Simon

1987), was limited to Forest Service land and did not include private land.

Consequently, we chose to map the forested vegetation from historic forest maps

rather than use plant associations. We assumed that these historic maps reflected

a condition less impacted than present day, especially in the higher elevation forested areas. These maps also showed the results of disturbances such as fire, logging, and grazing. Historic forest county maps were digitized by the Pacific Northwest

Region (USDA Forest Service 1949, 1952, 1957). The original maps were at a scale

of 1:63,360. The counties and original date of mapping are included in the following

tabulation:

Oregon Washington

County Date County Date

Union 1958 Asotin 1935

Umatilla 1958 Columbia 1935

Wallowa 1957 Garfield 1935

Grant 1960

Wheeler 1953

Crook 1952

Baker 1957

75
These county forest maps were very helpful. In addition to these digital maps, two

paper maps, Forest Type Map of Oregon and Forest Type Map of Washington at a

scale of approximately 1:250,000, were used (Andrews and Cowlin 1936a, 1936b;

USDA Forest Service 1936). Both surveys were the result of section 9 of the McNaryMcSweeney Research Act of 1928, which called for a comprehensive and detailed

investigation of the existing timber resources by volume and area. The surveys used

all existing information on distribution of forest types and made type maps of all forest

areas in the region for which no usable data existed (USDA Forest Service 1936,

1949, 1952, 1957).

The digital forest maps by county were easier to use because they could be plotted

at our mapping scale of 1:100,000. We thought that they might contain more accurate

information being newer and more detailed than the Andrews and Cowlin maps; however, the Andrews and Cowlin maps represented a less human-impacted condition in

the forested areas. In many places, logging was confined to the lower elevations until

the 1950s (Oliver and others 1994). Because of registration difficulties with the 1936

maps, we adjusted some lines by using elevation and aspect information from the

literature.

Literature about the vegetation communities (Franklin and Dyrness 1988; Gannett

1902; Hall 1973a, 1973b; Johnson and Clausnitzer 1992; Johnson and Simon 1987;

Johnson and others 1994; Munger 1917) was used to resolve conflicts between the

two maps. For example, juniper has increased its range partly because of fire suppression. This was evident in comparing the 1930s and 1950s mapping. In this case,

we used the 1936 map to define the juniper areas. We knew that the moister ponderosa pine-dominated sites are often grand fir-climax sites historically maintained by

frequent low-intensity ground fires7

 (Lehmkuhl and others 1994). Johnson and

Clausnitzer (1992) describe these areas as grand fir plant associations and document

the early serai role of ponderosa pine in the section, “Successional Relationships.”

These areas were delineated as ponderosa pine on the landscape-level ecoregion

map because we intended our mapping to reflect the role of fire as a natural disturbance. Johnson and others (1994) state that “throughout the presettlement period, fire

was an integral part of the maintenance and function for the majority of eastside

ecosystems.”

The intent of the 1936 map was to map timber resources; therefore, the extent of

subalpine fir forests was unimportant. Subalpine fir was mapped with noncommercial

rocky areas on the 1936 maps. This mapping convention caused some difficulties for

us. Fortunately in the accompanying forest statistics for each county (Bolles 1937;

Buell 1937; Litchfield 1937; Moravets 1937; Pelto 1937; Sankela 1937a, 1937b;

Wolfe 1937), subalpine fir and noncommercial rocky areas were not combined. We

used these numbers and the later forest mapping to evaluate and adjust our map

delineations.

7

 Hall, F.C. 1991. Ecology of fire in the Blue Mountains of

eastern Oregon. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Region. 27 p.

Unpublished report. On file with: Pacific Northwest Research

Station, Forestry Sciences Laboratory, 3200 SW Jefferson

Way, Corvallis, OR 97331.

76
The digital map and manual of Kagan and Caicco (1992), developed as part of the

Oregon Gap Analysis Program, was marginally useful because it represented actual

conditions after decades of land use and vegetation conversion. Mainly it was used

for additional information when large patches of larch, Douglas-fir, lodgepole pine,

or noncommercial rocky areas were in question. The map was compiled by visually

interpreting Landsat MSS false-color infrared positive photographic prints. There were

registration problems with this map, and it is being redone.

We defined five forest zones—Juniper, Ponderosa Pine, Douglas-Fir, True Fir, and

Subalpine Fir. We felt that by using vegetation zones instead of a finer scale classification, the variability caused by disturbance history was lessened. Table 10 lists the

major species occurring in each forest zone and also gives an approximate elevation

and annual precipitation range for each zone. The primary sources for the table and

descriptions of each zone were Franklin and Dryness (1988), Hall (1973a, 1973b),

Johnson and Clausnitzer (1992), Johnson and Simon (1987), and Johnson and others

(1994). Only Franklin and Dryness (1988) provide information on serai and climax

forest species composition. The table is intended only as a general guide to species

composition.

Vegetation in the study area is greatly influenced by the presence or absence of marine influence. Elevation ranges given for most zones apply to the entire study area.

Although zones will usually start higher in areas not maritime influenced, the maritimeinfluenced zone subregion (insert B) indicates the extent of maritime influence. Interfingering among contiguous forest zones also is important in this area. More mesic

zones may extend farther into dry climates by taking advantage of north-facing slopes

and stream margins and ascend farther on exposed slopes and ridges. The presence

of deep soil with high moisture-holding capacity, such as formed from ash, also allows

vegetation to extend into areas with less precipitation.

Occupying the zone between the ponderosa pine and the grassland or sagebrush

zones was the western juniper zone (map units beginning with “j”). This zone occurred only in the John Day basin of our study area, perhaps because of continental

influence. This is the driest “forested” zone with most of the precipitation falling during

winter. Soil is typically light-colored, coarse-textured sandy loam and low in organic

matter.

Ponderosa pine is climax vegetation on the warmest and driest forest sites and is a

major serai component in the Douglas-fir and grand fir series. Our ponderosa pine

zone contained both climax and serai ponderosa pine forests (map units beginning

with “p”)- The thick bark of ponderosa pine allows it to withstand ground fires better

than the thin-barked true firs. Climax ponderosa pine forest occurs on coarse, sandy

soils and where cracks in the bedrock permit trees to tap underlying moisture. Soils

on these sites usually are dry at depths of 10 to 61 centimeters (4 to 24 in) for 60 or

more consecutive days during summer and autumn. Ponderosa pine forests grow on

three distinctive types of soil. The ash soil is coarse, but it has a high moistureholding capacity. Organic matter is concentrated near the surface and declines rapidly

with depth. Soil derived from basalt, andesite, and clay sediments is moderately deep,

dark colored, fine, and loamy. This soil is easily compacted and puddles when wet.

77
Table 10—Characteristics of the forest zones

Forest zone,

elevation range, and

annual precipitation range Tree species Shrub species Grass and forb species

Juniper Western junipre (Juniperus Bitterbrush (Purshia Idaho fescue (Festuca

occidentalis) tridentata) idahoensis)

760-1400 m Big sagebrush Bluebunch wheatgrass

(2,483-4,593 ft) (Artemisia tridentata) (Agropyron spicatum)

Mountain-mahogany Elk sedge (Carex geyeri)

20-30 cm (8-12 in) (Cercocarpus)

ledifolius)

Ponderosa pine Ponderosa pine (Pinus Mountain-mahogany Elk sedge (Carex geyeri)

ponderosa) (Cercocarpus Idaho fesuce (Festuca

900-1500 m Grand fir (Abies grandis) ledifolius) idahoensis)

(2,953-4,921 ft) White fir (Abies concolor Common snowberry Pinegrass (Calamagrostis

(Gord & Glend.) Lindl) (Symphoricarpos rubescens)

35-76 cm Western larch (Larix albus) Wheeler’s bluegrass (Poa

(14-30 in) occidentalis) Mountain snowberry nervos)

Douglas-fir (Psuedotsuga (Symphoricarpos Bluebunch wheatgrass

menziesii) oreophilus) (Agropyron spicatum)

Lodgepole pine (Pinus Bitterbrush (Purshia

contorta) tridentata)

Western white pine (Pinus Mountain big sagebrush

monticola Dougl. ex D. Don) (Artemisia tridentata

vaseyana)

Douglas-fir Douglas-fir (Pseudotsuga Rocky Mountain maple Western fescue (Festuca

menziesii) (Acer glabrum) occidentalis)

Ponderosa pine (Pinus Mallow ninebark Pinegrass (Calamagrostis

ponderosa) (Physocarpus rubescens)

Western larch (Larix malvaceus Elk sedge (Carex geyeri)

occidentalis) Big huckleberry

Lodgepole pine (Pinus (Vaccinium

contorta) membranaceum)

Mountain snowberry

(Symphoricarpos

oerophilus)

Common snowberry

(Symphoricarpos

albus)

Birchleaf spiraea

(Spiraea betulfolia)

Ocean-spray (Holodiscus

discolor (Pursh)

Maxim.)

78
Table 10—Characteristics of the forest zones (continued)

Forest zone,

elevation range, and

annual precipitation range Tree species Shrub species Grass and forb species

True fir Grand fir (Abies grandis) Pacific yew (Taxus Oak-fern (Gymnocarpium

White fir (Abies concolor) brevifolia) dryopteris (L.) Newm.)

1500-2000 m Ponderosa pine (Pinus Thimbleberry (Rubus Coolwort foamflower

(4,921-6,562 ft) ponderosa) parviflorus) (Tiarella trifoliata

Lodgepole pine (Pinus Twinflower (Linnaea unifoliata L.)

63-115 cm (25-45 in) contorts) borealis) Hooker’s fairy bells

Western larch Big huckleberry (Disporum hookeri

(Larix occidentalis) (Vaccinium (Torr.) Nicholson)

membranaceum)

Douglas-fir (Pseudotsuga

menziesii) Sword-fern (Polystichum

Western white pine (Pinus Grouse huckleberry munitum (Kaulf.) Presl)

monticola) (Vaccinium scoparium) Queen’s cup beadlily

(Clinton ia uniflora)

Pinegrass (Calamagrostis

rubescens)

Columbia brome (Bromus

vulgaris (Hook.) Shear)

Lupine (Lupinus L.)

Elk sedge (Carex geyeri)

Ginger (Asarum caudatum

Lindl.)

Subalpine fir Subalpine fir (Abies lasiocarpa) Big huckleberry Heartleaf arnica (Arnica

Engelmann spruce (Picea (Vaccinium cordifolia Hook.)

1300-1700 m engelmannii) membranaceum) Queen’s cup beadlily

(4,265-5,577 ft) Lodgepole pine (Pinus Fool’s huckleberry (Clintonia uniflora)

contorta) (Menziesia ferruginea Sidebells pyrola (Pyrola

Western larch (Larix Smith) secunda L.)

occidentalis) Grouse huckleberry Elk sedge (Carex geyeri)

Whitebark pine (Pinus (Vaccinium scoparium)

albicaulis)

Douglas-fir (Pseudotsuga

menziesii)

79
Surface erosion is a problem on slopes greater than 30 percent. The soils most sensitive to erosion are derived from rhyolite, andesite, granitics, glacial till, and outwash.

These soils are coarse, loamy, and shallow-to-deep with low organic matter content

and low water-holding capacity. On cooler, moister sites, the soil has more organic

matter.

A mixed ponderosa pine-grassland or ponderosa pine-shrubland zone was identified

(map units beginning with “m”) in areas at the lower edge of the ponderosa pine zone

where the two zones intermix. In this area, ponderosa pine is confined to a fringe of

trees along canyon sides, draws, and north-facing hillsides (Munger 1917). The geographic extent of this area (about 3500 square kilometers [1,351 mi2

]) called for a

new zone rather than dividing it between the ponderosa pine and grassland zones. A

separate shrubland zone was not identified. Species for the shrubland component of

the ponderosa pine-shrubland zone are found in table 11.

A Douglas-fir zone is identified by some authors (Hall 1973, Harvey and others 1994,

Johnson and Clausnitzer 1992, Johnson and Simon 1987, Johnson and others 1994).

Franklin and Dyrness (1988) say that its occurrence is conjectural except in parts of

the Wallowa Mountains. Because of its wide ecological aptitude, Douglas-fir occurs in

both the ponderosa pine and true fir zone; and it was difficult to differentiate based

on the available maps. For this reason, we delineated a Douglas-fir zone only in the

Wallowa Mountains (map units beginning with “d”).

The upper elevational limit of the ponderosa pine gives way abruptly to a different,

much denser stand of other species (Munger 1917) comprising the true fir zone (map

units beginning with “t”). This zone included both grand fir (found in the northeastern

part of the study area) and white fir (found farther south). Franklin and Dryness

(1988) treat these areas similarly because “these two species and the zones they

typify occupy analogous positions synecologically and environmentally in their respective areas.” To denote both white fir and grand fir in the name, we used the term “true

fir.” We recognized that subalpine fir is also a “true fir.” Because subalpine fir occupies a higher elevation and colder environment, we mapped it separately from our

“true fir” category. The true fir zone is characterized by neither temperature nor moisture extremes. It is wetter and cooler than the ponderosa pine zone and has higher

temperatures and less accumulation of snow than the subalpine fir zone. Soil is

usually moderately deep because of the accumulation of volcanic ash. These soils

are very fertile with rapid infiltration, high water-storage capacities, and good aeration.

The subalpine fir zone is the coolest and moistest forest zone with a deep winter

snowpack (map unit beginning with “f”). Subalpine fir forests may be found below

this elevational range in frost pockets and areas affected by cold air drainage,

such as glaciated valley bottoms. Soils are coarse and stony with well-developed,

relatively thin humus layers, and low fertility. They are credible when exposed to

wind. Our subalpine fir zone contained a whitebark pine zone analogous to the

juniper zone at the lower forest fringe.

80
Table 11—Species composition of the nonforested zones

Zone Dominant shrub species Dominant grass species

Aridic grassland Bitterbrush (Purshia tridentata) Needle and thread (Stipa comata Trin.

Basin big sagebrush (Artemisia tridentata spp. and Rupr.)

tridentata) Sandberg’s bluegrass (Poa sandbergii)

Indian ricegrass (Oryzopsis hymenoides

Thurb.)

Bluebunch wheatgrass (Agropyron spicatum)

Sagebrush Mountain big sagebrush (Artemisia tridentata Elk sedge (Carex geyeri)

spp. vaseyana (Nutt.) Idaho fescue (Festuca idahoensis)

Low sagebrush (Artemisia arbuscula (Nutt.)) Sandberg’s bluegrass (Poa sandbergii)

Stiff sagebrush (Artemisia rigida (Nutt.)) Bluebunch wheatgrass (Agropyron spicatum)

Xeric grassland Bluebunch wheatgrass (Agropyron spicatum)

Sandberg’s bluegrass (Poa sandbergii)

Mesic grassland Idaho fescue (Festuca idahoensis)

Prairie junegrass (Koelaria cristata Pers.)

Bluebunch wheatgrass (Agropyron spicatum)

Hood’s sedge (Carex hoodii)

Shrublands Ninebark (Physocarpus matvaceus) Bluebunch wheatgrass (Agropyron spicatum)

Common snowberry (Symphoricarpos albus) Idaho fescue (Festuca idahoensis)

Ocean-spray (Holodiscus discolor) Wheeler’s bluegrass (Poa nervosa)

Cherries spp. (Prunus L)

Mountain-mahogany (Cercocarpus ledifolius)

Alpine Alpine sagebrush (Artemisia tridentata spp. Green fescue (Festuca viridula)

vaseyana) Idaho fescue (Festuca idahoensis)

Elk sedge (Carex geyeri)

81
Information on vegetation in lower elevation, nonforested land was critically lacking

for this project. Historical forest maps showed only areas outside the forested areas

as “nonforested.” The map of Kagan and Caicco (1992) was of little help because

much of this area is now agricultural. Potential-vegetation community descriptions

from the county’s soil surveys were helpful. Differentiation between grass and sagebrush zones was sometimes difficult, especially in the Pleistocene Lake Basin subregion. Differentiation within these classes was not possible with the mapped information available, but many of these finer vegetation classes are expected to follow other

mapped landscape characteristics, particularly differences in soil depth and moisture.

Literature on nonforested vegetation was obtained from Daubenmire (1988), Franklin

and Dyrness (1988), Johnson and Simon (1987), and county soil surveys.

We divided the nonforested vegetation into zones starting with the warmest and driest: aridic grassland, sagebrush, grassland, and alpine. The choice of these classes

was based partly on the review of the scientific literature; greatly influencing the decisions was the availability of spatial data. The distinction among rigid, low, and big

sagebrushes and between grassland communities dominated by fescue and those

that are not would have been valuable for determining soil depth and moisture regime; however, maps showing these distinctions are not commonly available.

Table 11 shows the dominant species occurring in these zones. The primary

sources for the table and descriptions of each zone were Daubenmire 1988;

Dyksterhuis 1981; Franklin and Dryness 1988; Hall 1973a, 1973b; Harrison and

others 1962, 1973; Hosier 1983; Johnson and Makinson 1988; Johnson and others

1994; and Johnson and Clausnitzer 1992. The table is intended only as a general

guide to species composition.

The driest zone was the aridic grassland which occurred mainly in glaciofluviate deposits (map units beginning with “g” and containing “go/t,” “es,” “gfg,” “aca,” “loda/h,”

and “gfs”). The mean annual precipitation in this zone is usually less than 30 centimeters (12 in) per year.

The next driest zone, which we called the sagebrush zone, consists dominantly of

big sagebrush and bluebunch-wheatgrass (map units beginning with “s”). Even in

the driest part of this zone, there is virtually no bare ground in the undisturbed climax

(Daubenmire 1988). Soil is mostly loam or stony loam. In the John Day basin, the

sagebrush zone frequently abuts the juniper or ponderosa pine forested zones, possibly due to the influence of the colder, drier continental climate.

The grassland zone (map unit beginning with “g”) rises to an elevation of about 900

meters (2,953 ft). This zone is wetter than the sagebrush zone. Most of the Columbia

Plateau and some basins within the Blue Mountains are dominated by grassland communities. This zone could be broken into the mesic grasslands where Idaho fescue

forms the climax communities and the xeric grasslands where Idaho fescue is absent

and bluebunch-wheatgrass dominates if maps to show this distinction were available

for the study area. Table 11 gives the species composition for these two grassland

zones. The wetter grasslands areas are found at upper canyon elevations, on northfacing aspects at lower elevations, and on deeper soils of the ridges where moisture

is retained longer into the summer drought period.

82
The alpine zone included the alpine sagebrush and green fescue in the high

Wallowas and alpine fescue communities in the Blue Mountains (map units

beginning with “a”). The elevation ranges from 1859 to 2499 meters (6,100 to

8,200 ft). This zone was large enough to be mapped only in the Wallowa Mountains. On the granitic soils, rapid drainage leads to low vegetative productivity, making

this zone more erosive; on lava soils, there is more herbage and thus less erosion.

Geology and geomorphology—Geology and geomorphology play a strong role in

controlling stream-habitat characteristics, especially substrate, habitat complexity,

and water quantity. Most geology maps are based on rock type and age, and mapping units may incorporate rocks with vastly different engineering or hydrologic properties. These groupings may be due to different mapping goals, units too complex to

map lithologies, and map scale and resolution. Engineering and hydrologic properties such as joint structure, stratigraphy, credibility, porosity, and permeability were

more important for our purposes, making it necessary to interpret geology maps for

relevance to fishery biology and stream ecology.

A 1:500,000-scale geology map (Walker and Macleod 1991) of the State of Oregon,

available in digital form, was useful. The map was originally produced at 1:250,000

and later reduced to 1:500,000. For the purposes of this project, the detail of the map

was adequate. We recognized, however, that this map was not intended to be plotted

at the 1:100,000 scale of this project. Lacking other economically feasible options, we

used the map and made adjustments along the way. The most noticeable problem

was poor registration, especially seen in the alluvial areas. When working with the

geology layer, each 1:100,000 map sheet was manually reregistered to place the

alluvial areas next to rivers, requiring about a 1- to 2-centimeter (0.39- to 0.78-in) shift

in both the x and y directions. A draft geology map of southeast Washington8

 was

available in digital form although it was coarse scale. Many local 1:24,000- to

1:250,000-scale maps were used to adjust the lines and resolve questionable

areas.

Geologic mapping relies on topographic maps as their base (Weissenborn 1969), because geology is not usually a surface phenomenon. We frequently used topography

to adjust our lines where it was evident that geology would follow a topographic feature. We used many reports on geology (Baker and others 1991; Barrash and others

1980; Bishop 1995; Bishop and others 1992; Brooks 1979; Ferns 1985; Gonthier and

Bolke 1993; Hampton and Brown 1964; Hodge 1942; Hogenson 1964; Merriam 1901;

Newcomb 1965; Oles and Enlows 1971; Orr and others 1992; Reidel and Hooper

1989; Smith and others 1941; Taubeneck 1957; Thayer 1990; Walker 1990a, 1990b;

Walker and Robinson 1990; Weissenborn 1969; Whiteman and others 1994; WRB

1963; WRD 1988) to help us understand the processes and potential topographic

manifestations of the geology. In addition, these reports frequently had small schematic maps and descriptive information that was invaluable in delineating boundary

lines and describing the geologic properties from which we could infer potential importance to stream-habitat characteristics. By using existing maps and literature, we

have attempted to delineate and describe the characteristics of the rocks or formations that potentially influence stream habitat.

8 Johnson, B.R.; Derkey, P.D. 1993, Geological map

compilation of southeast Washington. Digital data. Draft

dated 1993 to Sharon Clarke. On file with: Spokane, WA:

U.S. Geological Survey.

83
The hydrologic properties of a geologic formation are not determined solely by the

permeability or porosity of a rock but may reflect the joint structure (Gregory and

Walling 1973). Stratigraphy also plays a large role in the movement of water through

the bedrock. For example, basalt is not generally porous or permeable, but it commonly has a hexagonal joint pattern that transmits water vertically, and the Columbia

River basalt frequently has extensive, lateral, permeable sedimentary deposits or

paleosols between the flows. Both jointing and intrabeds contribute to the importance

of the Columbia River basalts in providing ground water to streams.

Mineral composition strongly influences the weathering rate, soil productivity, and rate

of erosion. The stratigraphy is important, for example, where the resistant basalt rests

on top of highly erodible ash such as in the John Day Formation. Focusing only on

the top layer of basalt might mask the true erosiveness of the area. Stratigraphy at

any single location is impossible to determine from maps where only the top layer of

geology is mapped. The geomorphology of an area strongly influences the movement

of water and erosion. Discussion of geomorphology is linked to both geology and

topography.

The following section describes the major geologic types found in the study area and

summarizes their origin, spatial extent, and properties relevant to stream habitat. In

keeping with geologic convention, the units will be discussed in order of age. The preCenozoic rocks include the metasedimentary and metavolcanic rocks associated with

exotic island arcs, subduction and collision of the Pacific oceanic plate with the North

American continental plate, and plutonic intrusions. These rocks outcrop in only about

10 to 15 percent of the Blue Mountains (Walker 1990b). The rocks of the Cenozoic

Era are divided into the Tertiary and Quaternary Periods. The Tertiary Period was a

time of major volcanic activity that formed the Clarno, John Day, Columbia River

basalt, and Strawberry Formations. The Quaternary was a time of alpine glaciation

and fluvial-generated alpine erosion with deposition of sediments in basins that

shaped the current landscape of the study area.

Pre-Cenozoic Era—The pre-Cenozoic rocks (320 to 65 million years ago) are a direct

result of plate tectonics. Brooks (1979) and Bishop (1995) discussed these preCenozoic deposits. Most of Oregon and Washington were once part of the Pacific

Ocean. The rocks exposed in Hells Canyon and in much of the higher elevations of

Wallowas, Elkhorns, and old mountains in the region were formed as volcanic islands.

Sediments, including limestone, conglomerate, sandstones, and shales, accumulated

from erosion of this island system, eventually burying the old volcanic rocks. The remnants of the old volcanic arc are called the Wallowa and Olds Ferry terranes, approximately 300 to 200 million years in age. (A terrane is a coherent package of rock built

in one place through one kind of geologic process.) The subduction zone and portions

of oceanic crust trapped and deformed between volcanic arcs is called the Baker

terrane, and it is about 300 to 200 million years in age. The less-deformed package

of sedimentary rocks that overlie the Baker terrane is called the Izee terrane, and it

consists of shale and fine sandstone exposed in the Aldrich Mountains. As the terranes collided with the North American plate, older deeply buried and deformed volcanic rocks were heated and subjected to high pressure. Greenstones and sediments

melted and rose into the surface of the overriding plate producing the granitic plutons

that now form the core of the Wallowas and northern part of the Elkhorn Mountains.

84
The Baker terrane consists of argillite, chert, conglomerate, limestone, greenstone,

sea-floor and island arc plutonic rock, high-pressure schist and serpentinite from both

crustal and supracrustal rocks that have been severely broken up, rearranged, and

deformed. The crustal rocks are called a melange composed of ultramafic rocks, gabbra, quartz diorite, and albite granite severely deformed by folding and faulting. Melanges typically have a matrix of serpentinite, a scaly, slippery, green rock (map units

containing “sp”). The largest exposures of these rocks are found in the Greenhorn,

Elkhorn, Strawberry, and Aldrich Mountains and the Ochoco Mountains near Antone.

The presence of serpentinite may increase the risk of landslides due to its slippery

nature, lack of soil nutrients, and low vegetative productivity.

The Canyon Mountain complex in the Strawberry Mountains is considered island arcrelated, not derived from ocean crust. In its uppermost sections, it consists mainly of

gabbro, the coarse-grained equivalent of basalt. Gabbro weathers and erodes more

rapidly than granitic rocks (Chesterman 1979) and like serpentine produces clays that

are expandable, thus producing slide-prone soils.

Other lithologies common in the chaotic Baker terrane include ribbon chert and siliceous argillite—hard, silica-rich layers separated by thin, dark, fine-grained layers of

shale (map units containing “ag”). This shale component makes the argillite erodible.

These rocks are a major part of the Elkhorn and Greenhorn Mountains.

The sedimentary rocks in the Aldrich Mountains are composed of thick deposits of

shales and fine sandstones similar to the Elkhorn Ridge argillite, except less

metamorphosed—a composition that makes them more crumbly. These rocks are

part of the Izee terrane.

The Wallowa-Seven Devils terrane consists of volcanic, plutonic, and sedimentary

rocks that have been somewhat metamorphosed. The volcanic rocks were originally

basalt, andesite, and dacite slightly metamorphosed to greenstone (map unit containing “vm”). The sedimentary rocks include shales and sandstone of the Hurwal

Formation and Lower sedimentary series as well as Martin Bridge Limestone composed of limestone deposited in shallow water and the Hurwal Formation made up

mostly of shale with some sandstone and a few conglomerates (map units containing

“svm” and “se”). These rocks were best exposed in the northern Wallowa Mountains.

Large bodies of intrusive rocks called batholiths intruded the Baker and WallowaSeven Devils terranes. These rocks have the appearance of granite, but because

they are rich in feldspar and contain little quartz, they are technically not true “granite.” The name “granitic” or “granitoid” is more correct. The largest, the Wallowa batholith, is found in the core of the Wallowa Mountains. Other granitic intrusions include

Bald Mountain and Battle Mountain and an unnamed stock along the John Day River

near the Ritter Hot Springs. The intrusive rocks range from gabbro to granite, but

feldsparbiotite-rich lithologies (tonalite and granodiorite) form most of the exposure.

The intrusions formed contact halos where the surrounding rocks have been strongly

foliated and metamorphosed (Weissenborn 1969). Erosion later stripped off most of

the sedimentary rocks covering these intrusive rocks (Smith and others 1941). The

surrounding sedimentary and volcanic rocks have been metamorphosed to various

degrees, which made it difficult to generalize about their properties. These rocks are

more resistant to erosion than they would be if unmetamorphosed. There is a wide

85
range of erodibility for metamorphosed rocks, however, depending on degree of metamorphism and origin. Usually the metamorphic volcanic rocks (that is, greenstone,

metamorphosed basalt, or gabbro) are resistant to erosion, whereas the metamorphosed sedimentary rocks (that is, slate, metamorphosed shale) are not. The rocks

classified as partly metamorphosed-sedimentary and volcanic rocks challenge even

these generalizations. We colored the coded units containing metamorphic rocks

similarly within vegetation zones but labeled them based on the type of rock that was

metamorphosed, that is, “svm” for sedimentary and volcanic rocks partly metamorphosed, “sm” for sedimentary rocks partly metamorphosed, and “vm” for volcanic

rocks partly metamorphosed.

Granitic outcrops are generally bold and well rounded (map units containing “in”).

The rock is massive, tight and poorly permeable, and weathers to a coarse sandy

rock waste (Hampton and Brown 1964). The abundance of minerals susceptible to

chemical weathering (calcium plagioclase feldspars) and mechanical disaggregation

(biotite) creates granular, friable, easily erodible soil and deep “grus.” Megahan (1972)

and Megahan and others (1992) have done several studies on the granitic rocks of

the related Idaho batholith. They note that granitic soils in the Western United States

are noted for their high erodibility because of their relatively coarse texture, lack of

cohesion, and occurrence on steep slopes. Their coarse texture accounts for the fact

that most of their sediment loads are carried as bedload. Most of the streams in

granitic areas are clear, only becoming slightly turbid during peak flows.

Cenozoic Era-Tertiary Period— Significant volcanism occurred during the Tertiary

Period. The Clarno Formation, about 50 to 35 million years old, is a thick sequence

of andesite flows, mudflows, breccias, andesitic to rhyolitic volcaniclastic rocks, and

tuffaceous sedimentary rocks. The Clarno Formation is part of map units containing

“cl” except the tuffaceous facies that is combined with other map units containing

tuff—”tu.” The formation occupies a large area of more than 4000 square kilometers

(2,485 mi2

) to the south of the Blue Mountains uplift and near the western margin of

the Blue Mountains ecoregion. A smaller area of about 400 square kilometers (248

mi2

) is found along the axis of the Blue Mountains uplift in southern Morrow County

(Walker and Robinson 1990). The Clarno Formation’s bimodal geographic distribution,

as well as its complexity and diversity of ages suggests that several different volcanic

periods may be represented.9

 Rock types with different rates of weathering contribute

to the unique terrain found in the Clarno Formation. The volcaniclastic, sedimentary

rocks in the Clarno Formation show a much higher degree of induration than those of

the younger, ash-rich, overlying John Day Formation. Clarno mudflow (lahar) deposits

frequently form steep bluffs ornamented frequently with balanced rocks (Merriam

1901). Topography developed on Clarno mudflows yields large, rough inclined surfaces, hogbacks, knobby hills, buttes, and V-shaped canyons. Resistant lavas are

peeled off in layers because of the alternation of resistant lavas and yielding sediments. Although Hodge (1942) said that the Clarno Formation is resistant to erosion,

some areas mapped as Clarno include andesite flows separated by tuff beds. Such

areas are susceptible to landsliding. Because of the diversity of rock types, any generalization about the stability of the Clarno Formation is probably inaccurate. In the

9 Personal communication. 1994. E. Bishop, geologist,

Oregon Watershed Health Program, 52040 Highway 203,

Union, OR 97883.

86
headwaters of the Grande Ronde River, there is a large area mapped as andesite,

dacite, and sedimentary rocks by Walker and MacLeod (1991) and Ferns and

Taubeneck (1994). We mapped this unit with the Clarno Formation due to similarity

in rock types.

The John Day Formation was laid down over the eroded surface of the Clarno Formation (map units containing “tu”). The John Day Formation is very distinctive, and much

has been written about it. It is an assemblage of tuffaceous sedimentary rocks, air

fall and ash-flow tuff and sparse olivine-rich basalt lava flows (Robinson and others

1990). The John Day Formation is restricted to the lowland areas of the John Day

basin (Thayer 1990) and ranges in depth from a meter to more than 610 meters (a

few feet to 2,000 ft).

Landslides are common along the steep stream-cut slopes incised into the John Day

Formation and some are immense. Water flows through the heavy basalt that caps

the John Day Formation and soaks the tuffs below causing the basalt to slip, creep,

and landslide (Hodge 1942). Some of the largest landslides were mapped in map

units containing “Is.” Except in basins, soil does not form on the John Day Formation

because it is so pervious to ground water and blows away easily. Elephant-backs,

gullied slopes, pinnacles, and badlands comprise the topography in these areas

(Hodge 1942).

There were several other pockets of primarily tuffaceous sedimentary rocks in the

study area. Although they may be different ages, structurally we considered them to

be similar and have grouped them into map units containing “tu.” In the Grande

Ronde basin, Hampton and Brown (1964) report that some tuffs contribute to the rich

soils for which the upland district is famous. They note that the tuff weathers more

rapidly than the basalt and occupies topographic depressions bordered by steep

erosional escarpments.

The Columbia River Basalt Group (CRB) covers most of the Columbia Plateau and is

the most widespread geologic type in the study area. It consists of layer upon layer

of basalt flows that may be interspersed with extensive thin layers of sedimentary

deposits or paleosols. The sedimentary layers and soil were deposited in the time

between flows. In some places, these flows are more than 1524-meters (5,000-ft)

thick (Orr and others 1992).

The CRB (map units containing “cb”) is stratigraphically subdivided into the Saddle

Mountain, Wanapum, Grande Ronde, Picture Gorge, and Imnaha basalts (Walker

and MacLeod 1991). Over 90 percent of the CRB are the Grande Ronde basalts, the

result of eruptions between 15.5 and 19.5 million years ago. They are generally

crystal-poor, silica-rich, fine-grained basalt (Reidel and Hooper 1989). Grande Ronde

basalts are about 610 meters (2,000 ft) thick in the Grande Ronde Valley (Bishop and

others 1992). The Picture Gorge basalt with high magnesium and rapid weathering is

exposed in most of the John Day watershed. Because the Picture Gorge basalt tends

to be less resistant to erosion and has a significant exposure in the study area, we

delineated it as a separate category (map unit containing “pg”). Future work may find

the difference in erosion to be negligible when compared to other geologic types, and

it may prove meaningless to stream habitat.

87
Many basalt flows displayed a characteristic sequence of layers. The lower section

was characterized by huge vertical six-sided prisms. These prisms have a large diameter at the base and become smaller near the top. They break at right angles, and

breaks are more common near the tops of the flows. This characteristic fracture pattern produces large talus slopes of “brickbat” basalt. The tops of each flow are usually

covered by a mantle of vesicular-to-scoriacious lava. The basalt is usually fine and

even grained.

Basalt is not porous, but the porous and permeable tops of some flows, joint patterns,

and incomplete closures of one flow over another make the CRB a very important

aquifer (Hampton and Brown 1964, Hogenson 1964, Newcomb 1965, WRB 1963).

Streams without sources outside the Columbia Plateau flow only in summer where

springs emerge from the basalt; usually along axes of synclines (Newcomb 1965).

During low flow periods in the Upper Grande Ronde River basin, creeks draining

the older metamorphic and intrusive rocks of the Elkhorn Range are dry, but creeks

maintain a small, constant flow where the Columbia River Basalt overlies these older

deposits (Hampton and Brown 1964).

In northern Wallowa and Union Counties, there are some sedimentary beds interbedded with the CRB. These deposits were formed in shallow lakes and peat bogs

that formed on tops of the flows (Ferns 1985). These deposits can be as much as

91 meters (300 ft) thick. They crop out at only one small and remote location. The

presence of these lacustrine deposits beneath the basalt may make slopes more susceptible to landslides. Currently, we have mapped them separately as map units

containing “bl.”

Bower’s reaction series shows the sequence in the crystallization of a basaltic melt

(Foster 1975). Olivine is the first mineral to crystallize as the temperature falls; quartz

is the last. Conversely, olivine is the first to break down under chemical weathering

which contributes to unstable clays. This helps explain the differences in volcanic

rocks and associated soil. Basalt generally contains olivine; rhyolite contains quartz

and is the extrusive equivalent of granite. Andesite falls between. Quartz is resistant

to weathering; olivine is not. The minerals forming basalt are therefore more erodible

than the minerals forming rhyolite. Generalizations are difficult because the jointing

structure plays a significant part in determining erodibility. Only a small portion of the

study area in the southwestern corner contains significant amounts of rhyolitic rock

(map units containing “rh”). Significant amounts of andesite are found in the study

area.

The Strawberry Mountains andesite (map units containing “an”) is a product of volcanoes rather than the basalt floods that produced the Columbia River and Picture

Gorge Basalt Groups. This platy andesite does not have the well-developed vertical

joint system of basalt. It has random vertical joints, not well developed, and thin, discontinuous horizontal joints instead. Because of this, the andesite is relatively impermeable and does not have the aquifer properties of the basalt (Hampton and Brown

1964). The platy structure of this andesite may make it more erodible than the surrounding basalt (see footnote 9 10).

10 Personal communication. 1994. M.L. Ferns, geologist,

Oregon Department of Geology and Mineral Industries, 1831

1st Street, Baker City, OR 97184.

88
Concurrent with the volcanism, tectonism played a major role in the formation and deposits of the basins in the area. Two types of basins were formed. The earliest basins

were a result of synclinal downwarps in flow sequences of the CRB, that is, the Agency, Arlington, John Day, and Fox basins (Walker 1990a). The Ukiah basin is mapped

but not discussed by Walker (1990a) and was probably formed by faulting as well as

folding (see footnote 9) in a structural depression. The southern extent of this basin

was difficult to map. Soil and topographic maps showed the southern part to be

similar to the area around Ukiah. The geology maps, however, do not affirm this. The

Arlington, Agency, and Ukiah basins contain partially cemented gravel and interbedded tuffaceous sand and silt (map units containing “ca”). The margins of the Ukiah

basin are mapped in units containing “rca.” They have a thinner veneer of loess and

include some residuum. The lower elevations of the Arlington and Walla Walla basins

are overlaid by thick layers of loess and glaciofluviate deposits, which will be discussed in the Cenozoic Era-Quaternary Period section. In the John Day basin, the

present Strawberry and Aldrich Mountains were raised 2 to 3 kilometers (1.5 to 2 mi)

above the valley floor by faulting along the John Day fault system. Clastic rocks and

tuffs from the Strawberry Mountains volcanoes washed out over the basalt and produced the Mascall Formation. Gravelly, sedimentary rocks from the rising mountains

filled the John Day Valley producing the distinctive Rattlesnake deposits (Thayer

1990, Walker 1990a). A prominent bed of welded tuff or ignimbrite is present in the

upper part of the Rattlesnake Formation (map unit containing “fs”). The Fox basin is

a structural trough confined by faults and a syncline. It contains rhyolitic tuff and pebble gravels in the northwest and thin basalt flows faulted with tuffaceous beds in the

south (map units containing “tu”).

The more persistent basins in this area are a result of faulting. The Yakima Folds, a

series of anticlinal ridges and broad, flat-floored synclinal valleys and basins, influenced the formation of the Walla Walla basin. The Grande Ronde basin is a grabencontaining, fine-grained, poorly drained lacustrine deposits (map units containing “la”).

Where streams enter the basin, bouldery alluvial-fan deposits occur (map units containing “af”). Along the edges of the fault scarp (map unit containing “fsc”) are the

colluvial deposits (map units containing “co”). The Wallowa Mountains were uplifted

by faulting on two sides causing their characteristic bowl shape and radial drainage

pattern (Smith and others 1941). Glaciation coupled with this uplift caused the mountain streams to become deeply incised (Bishop 1995) and formed the Wallowa basin,

Joseph Upland. There is also a colluvium slope along the southwestern edge of the

basin.

Nonchannelized streams in the basins generally have a meandering pattern. The

major differences within the basins are in the drainage properties. The areas underlain primarily by gravels such as the alluvial fans have good drainage. Areas underlain by cemented alluvium or fine silt have low permeability.

Extensive folding also influenced other areas. Major structures such as the Blue

Mountains anticline and the Walla Walla and Umatilla synclines were formed. From

Prairie City to Dayville, the John Day River flows in a synclinal trough (USDI Bureau

of Reclamation 1985), and the Grande Ronde River flows through a synclinal trough

from Starkey to La Grande (Hampton and Brown 1964). This latter area is intersected

by many northwest striking faults (map unit containing “f/p”). The CRB in the Blue

Mountains is the southern upwarped and deformed part of the anticline (Baker and

others 1991). In these uplifted parts, streams have cut narrow, steep-walled canyons

89
where the rock is resistant. These valleys are marked by the stair-step edges of the

basalt layers. Several large upland areas remain undissected. Slopes on these plateaus are generally less than 15 percent; in the dissected canyons, slopes generally

range from 30 to 60 percent.

In places where the basalt is thin or underlain by the John Day Formation, much

wider valleys are formed (Orr and others 1992). The basalt in the Columbia Plateau

region is less deformed and underlies loess, lacustrine, and glaciofluviate deposits.

These deposits, however, have not modified the drainage pattern controlled largely

by the surface of the underlying basalt. The stream gradients are generally high

(> 15 m per km [50 ft per mi]), determined by the tilt of the basalt (Harrison and

others 1962).

Cenozoic Era-Quaternary Period—Generally, except for the basin fills, the geologic

deposits before this period have been indurated (consolidated and cemented). All the

deposits in the Quaternary Period consist of unconsolidated deposits. They are not

delineated on conventional bedrock geologic maps. These maps do not show quaternary deposits unless they are extensive, cover all bedrock units, or disrupt stratigraphy (as in a landslide). Gonthier and Bolke (1993) cite the mapping criterion of

Swanson and others (1987) to map sediments wherever they are sufficiently thick to

obscure the underlying basalt. The subjectivity of this statement makes it clear why

geologic maps differ considerably in the portrayal of these deposits. For our purposes,

we used geologic maps in conjunction with topographic maps to determine the

location of map-unit boundaries.

Glaciation had both direct and indirect effects on the study area. During the early part

of the Quaternary Period, the Pleistocene epoch, alpine glaciation carved, eroded,

and built morainal and fluvial deposits in the Wallowa, Elkhorn, Greenhorn, and

Strawberry Mountains. Large amounts of sediment filled the Grande Ronde Valley.

Indirectly, flooding from glacial Lake Missoula was responsible for shaping most of the

current landscape of the Columbia Plateau.

In the Strawberry Mountains, glaciers sculpted the principal valleys above 1524

meters (5,000 ft) forming U-shaped valleys (Thayer 1990). The radial valleys of the

Wallowa Mountains were widened and deepened by these glaciers. Glacial deposits

consisting of unsorted bouldery gravel, sand, and rock flour are found at the lower

end of these valleys and adjacent lowlands (map units containing “gl”).

The highest floodwater from Lake Missoula reached almost 366 meters (1,200 ft)

(Bretz 1969). Backflooding left deposits in many nonglacial valleys of the Snake River

such as the Tucannon and Asotin Rivers. Lake Lewis, formed by hydraulic damming

behind the Wallula Gap is largely responsible for the features of the Walla Walla

basin. Lake Condon, formed from a constriction around the Dalles, strongly influenced

the Umatilla basin. Hogenson (1964) described these deposits in the Umatilla basin,

and Newcomb (1965) described them for the Walla Walla basin. Glaciofluviate deposits are found below 229 meters (750 ft) (map units containing “es,” “gfg,” and

“gfs”). This area has been scoured by wind and water, and the surface of these deposits is dotted by many blowouts. Deposits consist of undifferentiated gravel, sand,

and silt. In the Walla Walla basin, these are called the Touchet Beds. Lacustrine deposits are found up to an elevation of about 350 meters (1,150 ft). They have been

severely dissected into long narrow ridges having steep north and east slopes and

strongly sloping south slopes (Harrison and others 1962), consisting mostly of

stratified lacustrine silt (map unit containing “aca”).

90
During these glacial periods, the weather was cold and windy, and vegetation was

sparse, ideal conditions for wind erosion (Brady 1990). Consequently, extensive loess

deposits blanketed the Columbia Plateau. These deposits are coarser and deeper

near the source, the glacial lake beds. Map units were differentiated by using depth

and moisture in these loessial areas (map units containing “lo”), as discussed in the

section on soil. In the dry areas with sparse vegetation, wind erosion is a major problem (Harrison and others 1962).

Although the recent alluvial valleys are relatively small (map units containing “al”),

we have delineated them because of their importance to fish.rr These alluvial deposits consist of sorted and unsorted silt, sand, and gravel. The low gradient of these

areas and the location of pools along the meanders makes them important refugia

and rearing habitat for fish. Because of their depositional nature, they are subject to

sedimentation from upstream sources. Where county soil surveys were available, we

defined these areas relatively easily. In other areas, we relied on their identification

from the geology, actual vegetation, and STATSGO soil map. Often, their width was

greatly exaggerated for cartographic purposes. We used topography to help us better

refine the boundaries. Areas less than 0.3 kilometer (0.2 mi) wide were not mapped.

We expect that some small alluvial valleys were missed by this process.

Topography—The preceding sections have covered the characteristics of topography; therefore, this section only discusses the topographic maps and digital data

used in this project. The components of topography—elevation, slope, and aspect—

are discussed in the sections on vegetation, climate, and soil. Because geomorphology is the science of topography, further discussion of topography is found in the section on geomorphology-geology.

We used 1:250,000 OEMs for Oregon and Washington with a 60- by 90-meter (66-

by 98-yd) resolution. Slope, aspect, and elevation were calculated from the OEMs.

Slope was broken into 6 slope classes, aspect into 8, and elevation into 10. Slope

classes were 0, 1 to 14, 15 to 29, 30 to 59, 60 to 89, and greater than 90 percent.

Elevation classes were 0 to 300 meters (0 to 328 yd), 300 to 600 (328 to 656), 600

to 900 (656 to 984), 900 to 1200 (984 to 1,312), 1200 to 1500 (1,312 to 1,640), 1500

to 1800 (1,640 to 1,968), 1800 to 2100 (1,968 to 2,296), 2100 to 2400 (2,296 to

2,624), 2400 to 2700 (2,624 to 2,952), and 2700 to 3000 (2,952 to 3,280). Aspect

classes were N, NE, E, SE, S, SW, W, and NW. We plotted a coarse-scale map of

slope, aspect, and elevation for the study area showing these broad spatial patterns.

The U.S. Geological Survey topographic maps, at 1:100,000, were indispensable to

interpret land-surface form, drainage patterns, slope, aspect, and elevation and were

used as base maps for this project.

11 Reeves, G.H. 1988. Distribution and abundance of fish

and fish habitat in Upper Elk River, 1985-1986. Draft report.

on file with: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Research Station, Corvallis, OR.

91
Conclusion The type and distribution of substrate; habitat complexity operating at many spatial

scales; the amount, timing, and quality of water; the type and amount of riparian vegetation; and interactions among biota are influenced by multiple landscape characteristics, sometimes acting synergistically to cause a stronger response or perhaps

acting antagonistically to mitigate the influence. It is impossible to predict stream

habitat at any given point based on a landscape classification because (1) landscape

properties are not black and white and do not operate independently but interact

either synergistically or antagonistically with other landscape properties; (2) the effects

of upslope processes are not the same throughout a basin, but differ depending on

the size of the stream, valley morphology, and slope; and (3) the influence of different

types and intensities of land uses needs to be considered.

Landscape-level ecoregions are a tool that may be useful in understanding and managing stream ecosystems. Years of process-level research will allow us to begin to

understand the direction and intensity of these multiple interacting processes. We

feel landscape-level ecoregions can help focus process-level research and that future

process-level research can help refine these regions in a positive feedback loop. Because in the interim, which inevitably will be a substantial timeframe, we are forced to

make management decisions, we have proposed these landscape-level ecoregions as

a level of stratification to help make local land management decisions. A landscapelevel classification can help identify (1) potential areas from which to pick reference

sites, (2) areas that may be sensitive to land use effects, (3) potential monitoring and

research sites, (4) areas to extrapolate the results from finer scale process-level research, and (5) the potential capacity of a stream.

Before incorporating landscape-level ecoregions into future research or management strategies, the landscape-level ecoregions should be evaluated. We agree

with Warren’s (1979) assessment that “potential capacity is a very abstract theoretical concept amenable only to very indirect and partial evaluation.” He also states

that “although in no ordinary sense can a classification be shown to be true or false,

validation of a sort is important.” We have chosen to use the word evaluate instead

of validate because the former expresses the element of judgment rather than proof.

By providing the logical underpinnings for the delineation of the map units, potential

users will be able to assess the usefulness of this classification for their specific project objectives. This critical evaluation is the first step in evaluating a classification.

The next step is a statistical analysis, as was done by Whittier and others (1988).

They used multivariate analysis of biotic assemblages, physicochemical measures,

species richness, diversity, and composition from small, minimally impacted streams

to evaluate the robustness of Omernik’s ecoregion classification in Oregon. Three approximately 100-meter-long (109-yd-long) reaches that encompassed complete sets

of the characteristic stream habitat types for that site were sampled for six streams

within each ecoregion. They found that as a whole, streams within an ecoregion tend

to be like other streams in that region and unlike streams in other regions. The principal components analysis (PCA) ordination for physical habitat shows regional patterns; however, the distribution of the Blue Mountains and Columbia Basin12

ecoregion’s streams do not form a tight cluster pattern. Finer scale classifications

(that is, subregions and landscape-level ecoregions) may further explain some of the

variability within ecoregions.

12 Now referred to as the Columbia Plateau ecoregion.

92
Ongoing research is focusing on evaluating the usefulness of landscape-level

ecoregions for assessing the variability of stream habitat and fish distribution by

using survey data. Based on this and future work, it may be advantageous to combine some regions if they are physically similar and respond to stresses similarly. Regions also may be combined to meet specific project goals. Survey data should be

both spatially and temporally representative of potential stream capacity. The best

indicator of the potential capacity of a stream results from analyzing fish distribution

and stream-habitat survey data from streams in a relatively unimpacted condition.

Data can be from either historic or present surveys, and we recognize that data of

this nature is limited, especially for low-elevation areas. Warren (1979) states “if a

classification is to serve management purposes, systems within a class must respond

similarly to similar environmental conditions including resource utilization and environmental management.” Following the logic of Warren (1979), data from disturbed

streams may help evaluate the landscape delineation because just as the potential

capacity of a stream may differ among regions, reaction to disturbance also may

differ among regions. Because the reaction of a stream to disturbance is frequently a

 simplification of the channel (Bisson and others 1992, Henjum and others 1994,

Hicks and others 1991), evaluating significant differences in stream habitat characteristics among regions and understanding the potential capacity of a stream is more

difficult. The response of a stream to disturbance, however, also varies with timing

and character of last disturbance as related to natural disturbance regime. In addition,

using data from disturbed streams requires knowledge of land use history. For example, the headwaters of the Upper Grande Ronde River have historically been

dredge mined (Mclntosh and others 1994). Stream-habitat survey data from 1941

showed no large pools in this area. Recent resurveys—(1990), found several large

pools in the same stretch of rivers. Most of these pools, however, were attributed to

the artificial pool-forming structures added to enhance habitat.13 Without knowledge

of these events, erroneous conclusions could be drawn from analysis of these

stream-habitat data.

Future work should focus on identifying the potential of a system by using reference

sites, historical stream data, and expert knowledge and grappling with the issues of

differences in the magnitude of upslope and upstream effects. We hope that more

work also will be done on classifying watersheds from their mix of ecoregions,

identifying appropriate questions for different scales in the hierarchy, and overlaying

information on human disturbances to assess the capability of ecosystems in each

ecoregion to deal with different types and intensities of stressors.

13 Personal communication, 1995. Bruce McIntosh, research

associate, Department of Forest Science, Oregon State

University, Corvallis, OR 97331.

93
Literature Cited Andrews, H.J.; Cowlin, R.W. 1936a. Oregon: northeast quadrant [forest type].

Portland, OR: U.S Department of Agriculture, Forest Service, Pacific Northwest

Forest and Range Experiment Station. 1:253,440; Lambert projection; colored.

Andrews, H.J.; Cowlin, R.W. 1936b. Washington: southeast quadrant [forest type].

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Forest and Range Experiment Station. 1:253,440; Lambert projection; colored.

Baker, V.R.; Bjornstad, B.N.; Busacca, A.J. [and others]. 1991. Quaternary geology of the Columbia Plateau. In: Morrison, R.B., ed. The geology of North America.

Vol K-2: Quaternary nonglacial geology: conterminous U.S. Boulder, CO: The

Geological Society of America: 215-250.

Barrash, W.; Bond, J.G.; Kauffman, J.D.; Venkatakrisnnan, R. 1980. Geology of

the La Grande area, Oregon. Spec. Pap. 6. Portland, OR: State of Oregon, Department of Geology and Mineral Industries. 47 p.

Beschta, R.L. 1991. Stream habitat management for fish in the northwestern

United States: the role of riparian vegetation. In: Colt, J.; White, R.J., eds.

Bioengineering symposium; 1988; Portland, OR. Bethesda, MA: American

Fisheries Society: 53-58.

Beschta, R.L.; Bilby, R.E.; Brown, G.W. [and others]. 1987. Stream temperature

and aquatic habitat: fisheries and forestry interactions. In: Salo, E.O.; Cundy,

T.W., eds. Streamside management: forestry and fishery interactions. No. 57.

Seattle, WA: University of Washington, Institute of Forest Resources: 191-232.

Bilby, R.E. 1984. Characteristics and frequency of cool-water areas in a western

Washington stream. Journal of Freshwater Ecology. 2(6): 593-602.

Bishop, E.M. 1995. Mafic and ultramafic rocks of the Baker Terrane. In: Vallier, T.L.;

Brooks, H., eds. Geology of the Blue Mountains region. Professional Pap. 1438.

[Place of publication unknown]: U.S. Department of the Interior, Geological

Survey: 221-245.

Bishop, E.M.; Thompson, L.L.; Woodward, J. 1992. Sedimentation and tectonics

in the Grande Ronde Graben, northeast Oregon: a preliminary assessment.

Cordilleran section, 88th annual meeting; [Meeting dates unknown]; [Meeting

location unknown]. Eugene, OR: Geological Society of America. 7 p.

Bisson, P.A.; Bilby, R.E.; Bryant, M.D. [and others]. 1987. Large woody debris in

the Pacific Northwest: past, present, and future. In: Salo, E.O.; Cundy, T.W., eds.

Streamside management: forestry and fishery interaction. No. 57. Seattle, WA:

University of Washington: 143-190.

Bisson, P.A.; Nielsen, J.L.; Palmason, R.A.; Grove, L.E. 1982. A system of naming

habitat types in small streams, with examples of habitat utilization by salmonids

during low streamflow. In: Armantrout, N.B., ed. Acquisition and utilization of

aquatic habitat inventory information. Bethesda, MD: American Fisheries Society:

62-73.

94
Bisson, P.A.; Quinn, T.P.; Reeves, G.H.; Gregory, S.V. 1992. Best management

practices, cumulative effects, and long-term trends in fish abundance in Pacific

Northwest river systems. In: Naiman, R.J., ed. Watershed management: balancing

sustainability and environmental change. New York: Springer Verlag: 189-332.

Bjornn, T.C.; Reiser, D.W. 1991. Habitat requirements of salmonids in streams. In:

Meehan, W.R., ed. Influences of forest and rangeland management on salmonid

fishes and their habitats. Spec. Publ. 19. Bethesda, MD: American Fisheries

Society: 83-138.

Bolles, W.H. 1937. Forest statistics for Baker County, Oregon. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest and Range

Experiment Station. 10 p.

Bond, C.E.; Rexstad, E.; Hughes, R.M. 1988. Habitat use of twenty-five common

species of Oregon freshwater fishes. Northwest Science. 62(5): 223-232.

Brady, N.C. 1990. The nature and properties of soils. New York: MacMillan

Publishing Co. 621 p.

Bretz, J.H. 1969. The Lake Missoula floods and the channeled scablands. Journal

of Geology. 77: 505-543.

Brooks, H.C. 1979. Plate tectonics and geologic history of the Blue Mountains.

Oregon Geology. 41(5): 71-80.

Brooks, H.C.; Fern, M.L.; Mullen, E.D. 1982. Oregon: Granite quadrangle, Grant

County [geologic and gold deposits]. GMS-25. Reston, VA: U.S. Department of the

Interior, Geological Survey. 1:24,000; Lambert conformal conic projection; colored.

Brown, C.E.; Thayer, T.P. 1966. Oregon: Canyon City quadrangle, northeastern

[Geologic]. I-447. Washington, DC: U.S. Department of the Interior, Geological

Survey. 1:250,000; colored.

Brunengo, M. 1991. Rain-on-snow zones. Olympia, WA: Washington Department

of Natural Resources. 1:250,000; digital data.

Bryce, S.A.; Clarke, S.E. 1996. Landscape-level ecological regions: linking statelevel ecological frameworks with stream habitat. Environmental Management.

20(3): 297-311.

Buckhouse, J.C.; Gaither, R.E. 1982. Potential sediment production within vegetative communities in Oregon’s Blue Mountains. Journal of Soil and Water Conservation. March/April: 120-122.

Buell, E.D. 1937. Forest statistics for Wallowa County, Oregon. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest and Range

Experiment Station. 9 p.

Carlson, G. 1974. Soil resource inventory, basic soil information and interpretive

tables: Malheur National Forest. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Region. 177 p.

95
Carlson, G.; Rother, E. 1974. Soil resource inventory, atlas of maps: Malheur

National Forest. Portland, OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Region. 33 p.

Chesterman, C.W. 1979. The Audubon Society field guide to North American rocks

and minerals. New York: Alfred A. Knopf. 850 p.

Clarke, S.E.; White, D.; Schaedel, A.L. 1991. Oregon, USA, ecological regions

and subregions for water quality management. Environmental Management.

15(6): 847-856.

Cupp, C.E. 1988. Valley segment type classification for forested lands of

Washington. Timber, Fish and Wildlife Ambient Monitoring Program Report.

Olympia, WA: Washington Department of Natural Resources. 47 p.

Daubenmire, R. 1956. Climate as a determinant of vegetation distribution in eastern

Washington and northern Idaho. Ecological Monographs. 26(2): 131-154.

Daubenmire, R. 1988. Steppe vegetation of Washington. EB 1446. Pullman, WA:

Washington State University Cooperative Extension. 131 p.

Dyksterhuis, E.L. 1981. Soil survey of Grant County area, Oregon. Washington, DC:

U.S. Department of Agriculture, Soil Conservation Service. 131 p.

Dyksterhuis, E.L.; High, C.T. 1985. Soil survey of Union County area, Oregon.

Washington, DC: U.S. Department of Agriculture, Soil Conservation Service. 194 p.

Ehmer, L. [n.d.]. Soil resource inventory. Pendleton, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region, Umatilla National Forest. 305 p.

Evans, J.G. 1989. Oregon: Desolation Butte quadrangle, Grant and Umatilla Counties

[Geologic]. CQ-1654. Reston, VA: U.S. Department of the Interior, Geological

Survey. 1:62,500; Polyconic projection; colored.

Everest, F.H.; Beschta, R.L.; Scrivener, J.C. [and others]. 1987. Fine sediment

and salmonid production: a paradox. In: Salo, E.O.; Cundy, T.W., eds. Streamside

management: forestry and fishery interaction. No. 57. Seattle, WA: University of

Washington: 98-142.

Ferns, M.L. 1985. Preliminary report on northeastern Oregon lignite and coal

resources, Union, Wallowa, and Wheeler Counties. Salem, OR: State of Oregon,

Department of Geology and Mineral Industries; open-file report 0-85-2. 19 p.

Ferns, M.L.; Taubeneck, W.H. 1994. Oregon: Limber Jim, Union County [Geologic].

GMS-82. Reston, VA: U.S. Department of the Interior, Geological Survey.

1:24,000; Lambert conformal conic projection; colored.

Forest Ecosystem Management Assessment Team [FEMAT]. 1993. Forest ecosystem management: an ecological, economic, and social assessment. Portland,

OR: U.S. Department of Agriculture; U.S. Department of the Interior [and others].

[Irregular pagination].

96
Foster, R.J. 1975. Physical geology. Columbus, OH: Charles E. Merrill Publishing

Co. 421 p.

Franklin, J.F. 1992. Scientific basis for new perspectives in forests and streams. In:

Naiman, R.J., ed. Watershed management: balancing sustainability and environmental change. New York: Springer Verlag: 25-72.

Franklin, J.F.; Dyrness, C.T. 1988. Natural vegetation of Oregon and Washington.

Corvallis, OR: Oregon State University Press. 452 p.

Frissell, C.A. 1993. Topology of extinction and endangerment of native fishes in the

Pacific Northwest and California (U.S.A.). Conservation Biology. 7(2): 342-354.

Frissell, C.A.; Liss, W.J.; Warren, C.E.; Hurley, M.D. 1986. A hierarchical framework for stream habitat classification: viewing streams in a watershed context.

Environmental Management. 10: 199-214.

Gallant, A.L.; Whittier, T.R.; Larsen, D.P. [and others]. 1989. Regionalization as a

tool for managing environmental resources. EPA/600/3-89/060. Corvallis, OR:

Environmental Protection Agency, Environmental Research Laboratory. 152 p.

Gannett, H. 1902. The forest of Oregon. Professional Pap. 4, Series H, Forestry,

No. 1. Washington, DC: U.S. Government Printing Office; U.S. Department of the

Interior, Geological Survey. 36 p.

Gentry, H.R. 1991. Soil survey of Asotin County area, Washington, parts of Asotin

and Garfield Counties. Washington, DC: U.S. Department of Agriculture, Soil

Conservation Service. 376 p.

Gill, R.E. 1994. Sediment delivery to headwater stream channels following road

construction and timber harvest in the Blue Mountains, Oregon. Corvallis, OR:

Oregon State University. 59 p. M.S. thesis.

Gonthier, J.B.; Bolke, E.L. 1993. Summary appraisal of water resources of the

Umatilla Indian Reservation. Water-Resources Investigation Rep. 91-4087-P.

Portland, OR: U.S. Department of the Interior, Geological Survey. 54 p.

Gregory, K.J.; Walling, D.E. 1973. Drainage basin form and process: a geomorphological approach. New York: John Wiley and Sons. 456 p.

Gregory, S.V.; Lambert!, G.A.; Ermann, D.C. [and others]. 1987. Influence of

forest practices on aquatic production. In: Salo, E.O.; Cundy, T.W., eds. Streamside management: forestry and fishery interaction. No. 57. Seattle, WA: University

of Washington: 235-255.

Gregory, S.V.; Swanson, F.J.; McKee, W.A.; Cummins, K.W. 1991. An ecosystem

perspective of riparian zones. Bioscience. 41(8): 540-551.

Griffith, G.E.; Omernik, J.M. 1991. Alabama/Mississippi project: geographic research component: ecoregion/subregion delineation. Corvallis, OR: Environmental

Protection Agency, Environmental Research Laboratory. 27 p.

97
Griffith, G.E.; Omernik, J.M.; Rohm, C.M.; Pierson, S.M. 1994a. Florida regionalization project. Corvallis, OR: Environmental Protection Agency, Environmental

Research Laboratory. 76 p.

Griffith, G.E.; Omernik, J.M.; Wilton, T.F.; Pierson, S.M. 1994b. Ecoregions and

subregions of Iowa: a framework for water quality assessment and management.

Journal of the Iowa Academy of Science. 101(1): 5-13.

Gulick, C.W. 1994a. Connell Quadrangle, Washington [Geologic]. 1:100,000. [Place

of publication unknown]: Washington State Department of Natural Resources,

Division of Geology and Earth Resources; open-file report 94-14. 18 p.

Gulick, C.W. 1994b. Pullman Quadrangle, Washington-Idaho [Geologic]. 1:100,000.

[Place of publication unknown]: Washington State Department of Natural Resources, Division of Geology and Earth Resources; open-file report 94-6. 22 p.

Hall, F.C. 1973a. Plant communities of the Blue Mountains of eastern Oregon and

southeastern Washington: Pacific Northwest Region Area Guide 3-1. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 62 p.

Hall, F.C. 1973b. Plant communities of the Blue Mountains of eastern Oregon and

southeastern Washington: Pacific Northwest Region Area Guide 3-2. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 51 p.

Hampton, E.R.; Brown, S.G. 1964. Geology and ground-water resources of the

upper Grande Ronde River basin, Union County, Oregon. Geological Survey Water

Supply Pap. 1597. Washington, DC: U.S. Government Printing Office. 102 p.

Harrison, E.T.; Donaldson, N.C.; McCreary, F.R. [and others]. 1962. Soil survey

of Walla Walla County area, Washington. Washington, DC: U.S. Department of

Agriculture, Soil Conservation Service. 138 p.

Harrison, E.T.; McCreary, F.R.; Nelson, F.L. 1973. Soil survey of Columbia County

area, Washington. Washington, DC: U.S. Department of Agriculture, Soil Conservation Service. 88 p.

Harvey, A.E.; Geist, J.M.; McDonald, G.I. [and others]. 1994. Biotic and abiotic

processes in eastside ecosystems: the effects of management on soil properties,

processes and productivity. Gen. Tech. Rep. PNW-GTR-323. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Research Station.

71 p. (Everett, Richard L, assessment team leader; Eastside forest ecosystem

health assessment; Hessburg, Paul F., science team leader and tech. ed., Volume

III: assessment.)

Hawkins, C.P.; Kershner, J.L.; Bisson, P.A. [and others]. 1993. A hierarchical

approach to classifying stream habitat features. Fisheries. 18(6): 3-12.

Heede, B.H.; Rinne, J.N. 1990. Hydrodynamic and fluvial processes: implications for

fisheries management and research. North American Journal of Fisheries Management. 10:249-268.105

98
Henjum, M.G.; Karr, J.R.; Bottom, D.L. [and others]. 1994. Interim protection for

late-successional forests, fisheries, and watersheds: National Forests east of the

Cascade crest, Oregon and Washington. Bethesda, MD: The Wildlife Society.

245 p.

Hicks, B.J.; Hall, J.D.; Bisson, P.A.; Sedell, J.R. 1991. Responses of salmonids to

habitat changes. Spec. Publ. 19. American Fisheries Society: 483-518.

Hodge, E.T. 1942. Geology of north-central Oregon. Oregon State Monographs,

Studies in Geology, No. 3. Corvallis, OR: Oregon State College. 76 p.

Hogenson, G.M. 1964. Geology and ground-water resources of the Umatilla River

basin, Oregon. Geological Survey Water Supply Pap. 1620. Washington, DC:

U.S. Government Printing Office. 162 p.

Hosier, R.E. 1983. Soil survey of Morrow County area, Oregon. Washington, DC:

U.S. Department of Agriculture, Soil Conservation Service. 225 p.

Hynes, H.B.N. 1972. The ecology of running waters. Toronto, Canada: University

of Toronto Press. 555 p.

Johnson, C.G., Jr.; Clausnitzer, R.R. 1992. Plant associations of the Blue and

Ochoco Mountains. R6-ERW-TP-036-92. [Place of publication unknown]: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Region, WallowaWhitman National Forest. 164 p.

Johnson, C.G., Jr.; Clausnitzer, R.R.; Mehringer, P.J.; Oliver, C.D. 1994. Biotic

and abiotic processes of eastside ecosystems: the effects of management on

plant and community ecology, and on stand and landscape vegetation dynamics.

Gen. Tech. Rep. PNW-GTR-322. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research Station. 66 p. (Everett, Richard L,

assessment team leader; Eastside forest ecosystem health assessment;

Hessburg, Paul F., science team leader and tech. ed., Volume III: assessment).

Johnson, C.G., Jr.; Simon, S.A. 1987. Plant associations of the Wallowa-Snake

province: Wallowa-Whitman National Forest. R6-ECOL-TP-255A-86. [Place of

publication unknown]: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Region, Wallowa-Whitman National Forest. 399 p.

Johnson, D.R.; Makinson, A.J. 1988. Soil survey of Umatilla County area, Oregon.

Washington, DC: U.S. Department of Agriculture, Soil Conservation Service. 388 p.

Kagan, J.; Caicco, S. 1992. Manual of Oregon actual vegetation. Boise, ID:

University of Idaho, Idaho Cooperative Fish and Wildlife Research Unit. 186 p.

Lehmkuhl, J.F.; Hessburg, P.P.; Everett, R.L. [and others]. 1994. Historical and

current forest landscapes of eastern Oregon and Washington. Part 1: Vegetation

pattern and insect and disease hazards. Gen. Tech. Rep. PNW-GTR-328.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Research Station. 88 p. (Everett, Richard L., assessment team leader; Eastside

forest ecosystem health assessment; Hessburg, Paul F., science team leader and

tech. ed., Volume III: assessment).

99
Lichatowich, J.; Mobrand, L.; Lestelle, L.; Vogel, T. 1995. An approach to the

diagnosis and treatment of depleted Pacific salmon populations in Pacific Northwest watersheds. Fisheries. 20(1): 10-18.

Litchfield, W. 1937. Forest statistics for Union County, Oregon. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest and Range

Experiment Station. 11 p.

Lotspeich, F.B.; Platts, W.S. 1982. An integrated land-aquatic classification system.

North American Journal of Fisheries Management. 2: 138-149.

Marcot, B.C.; Wisdom, M.J.; Li, H.W.; Castillo, G.C. 1994. Managing for featured,

threatened, endangered, and sensitive species and unique habitats for ecosystem

sustainability. Gen. Tech. Rep. PNW-GTR-329. Portland, OR: U.S. Department

of Agriculture, Forest Service, Pacific Northwest Research Station. 39 p. (Everett,

Richard L., assessment team leader; Eastside forest ecosystem health assessment; Hessburg, Paul F., science team leader and tech. ed., Volume III:

assessment).

Margalef, R. 1960. Ideas for a synthetic approach to the ecology of running waters.

Int. Rev. Gesamten Hydrobiol. 45: 133-153.

Maser, C.; Sedell, J.R. 1994. From the forest to the sea: the ecology of wood in

streams, rivers, estuaries, and oceans. Delray Beach, FL: St. Lucie Press. 200 p.

Mclntosh, B.A.; Sedell, J.R.; Smith, J.E. [and others]. 1994. Management history

of eastside ecosystems: changes in fish habitat over 50 years. 1935-1992. Gen.

Tech. Rep. PNW-GTR-321. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station. 55 p. (Everett, Richard L., assessment team leader; Eastside forest ecosystem health assessment; Hessburg, Paul

F., science team leader and tech. ed., Volume III: assessment).

McNary-McSweeney Research Act. Act of May 22, 1928. 45 Stat. 699, as

amended; 16 U.S.C. 581 et seqq.

Meehan, W.R. 1991. Introduction and overview. In: Meehan, W.R., ed. Influences of

forest and rangeland management on salmonid fishes and their habitats. Spec.

Publ. 19. Bethesda, MD: American Fisheries Society: 1-15.

Megahan, W.F. 1972. Sedimentation in relation to logging activities in the mountains

of central Idaho. In: Proceedings, sediment yield workshop; 1972; Oxford, MS.

Oxford, MS: U.S. Department of Agriculture, Forest Service, Sedimentation

Laboratory: 74-82.

Megahan, W.F.; Monsen, S.B.; Wilson, M.D. [and others]. 1992. Erosion control

practices applied to granitic roadfills for forest roads in Idaho: cost effectiveness

evaluation. In: Land degradation and rehabilitation, vol. 3. New York: John Wiley

and Sons: 55-64.

Merriam, J.C. 1901. A contribution to the geology of the John Day basin. University

of California, Department of Geology Bulletin. 2(9): 269-314.

100
Miller, J.F.; Frederick, R.H.; Tracey, R.J. 1973. Precipitation-frequency atlas of the

western United States. Volume IX, Washington. Silver Spring, MD: U.S. Department of Commerce, National Oceanic and Atmospheric Administration. DNR

digital data 1:2,000,000.

Minshall, G.W. 1988. Stream ecosystem theory: a global perspective. Journal of the

North American Benthological Society. 7(4): 263-288.

Minshall, G.W.; Cummins, K.W.; Petersen, R.C. [and others]. 1985. Developments in stream ecosystem theory. Canadian Journal of Fisheries and Aquatic

Sciences. 42: 1045-1055.

Montgomery, D.R.; Buffington, J.M. 1993. Channel classification, prediction of

channel response, and assessment of channel condition. TFW-SH10-93-002.

Olympia, WA: State of Washington, Timber Fish and Wildlife. 84 p.

Moravets, F.L. 1937. Forest statistics for Wheeler County, Oregon. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and

Range Experiment Station. 10 p.

Munger, T.T. 1917. Western yellow pine in Oregon. Bull. 418. Washington, DC: U.S.

Department of Agriculture. 48 p.

Murphy, M.L.; Meehan, W.R. 1991. Stream ecosystems. In: Influences of forest and

rangeland management on salmonid fishes and their habitats. Spec. Publ. 19.

Bethesda, MD: American Fisheries Society: 17-46.

Naiman, R.J.; Beechie, T.J.; Benda, L.E. [and others]. 1992. Fundamental

elements of ecologically healthy watersheds in the Pacific Northwest coastal

ecoregion. In: Naiman, R.J., ed. Watershed management: balancing sustainability

and environmental change. New York: Springer Verlag: 127-188.

Nawa, R.K.; Frissell, C.A.; Ebersole, J.L.; Liss, W.J. 1991. Life history and

persistence of anadromous fish stocks in relation to stream habitats and

watershed classification. Portland, OR: Oregon Department of Fish and Wildlife;

Annual progress report; project F-122-R. 82 p.

Nehlsen, W.; Williams, J.E.; Licatowich, J.A. 1991. Pacific salmon at the

crossroads: stocks at risk from California, Oregon, Idaho, and Washington.

Fisheries. 16(2): 4-21.

Newcomb, R.C. 1965. Geology and ground-water resources of the Walla Walla

River basin, Washington-Oregon. Water Supply Bull. 21. [Place of publication

unknown]: State of Washington, Division of Water Resources. 76 p.

Oles, K.F.; Enlows, H.E. 1971. Bedrock geology of the Mitchell Quadrangle, Wheeler

County, Oregon. Bull. 72. Portland, OR: State of Oregon, Department of Geology

and Mineral Industries. 62 p.

101
Oliver, C.D.; Irwin, L.L.; Knapp, W.H. 1994. Eastside forest management practices:

Historical overview, extent of their applications, and their effects on sustainability

of ecosystems. Gen. Tech. Rep. PNW-GTR-324. Portland, OR: U.S. Department

of Agriculture, Forest Service, Pacific Northwest Research Station. 73 p. (Everett,

Richard L, assessment team leader; Eastside forest ecosystem health

assessment; Hessburg, Paul F., science team leader and tech. ed., Volume III:

assessment).

Omernik, J.M. 1987. Ecoregions of the conterminous United States. Annals of the

Association of American Geographers. 77(1): 118-125.

Omernik, J.M. 1995. Ecoregions: a spatial framework for environmental management. In: Davis, W.S.; Simon, T.P., eds. Biological assessment and criteria: tools

for water resource planning and decision making. Ann Arbor, Ml: Lewis

Publishers: 49-65.

Omernik, J.M.; Griffith, G.E. 1991. Ecological regions versus hydrologic units:

frameworks for managing water quality. Journal of Soil and Water Conservation.

46: 334-340.

O’Neill, R.V.; DeAngelis, D.L.; Warde, J.B.; Allen, T.F.H. 1986. Hierarchical

concept of ecosystems. Monographs in Population Biology 28. Princeton, NJ:

Princeton University Press. 235 p.

Orr, E.L.; Orr, W.N.; Baldwin, E.M. 1992. Geology of Oregon. 4th ed. Dubuque, IA:

Kendall/Hunt Publishing Co. 254 p.

Paulson, D.J. 1977. Ochoco National Forest soil resource inventory. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 347 p.

Pelto, W.E. 1937. Forest statistics for Grant County, Oregon. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest and Range

Experiment Station. 9 p.

Petersen, P.M.; Hen dry, A.; Quinn, T.P. 1992. Assessment of cumulative

effects on salmonid habitat: some suggested parameters and target conditions.

TFW-F3-92-001. Seattle, WA: University of Washington, Center for Streamside

Studies. 75 p.

Platts, W.S. 1980. A plea for fishery habitat classification. Fisheries. 5: 2-6.

Reidel, S.P.; Hooper, P.R. 1989. Volcanism and tectonism in the Columbia River

flood-basalt province. Spec. Pap. 239. Boulder, CO: The Geological Society of

America, Inc. 386 p.

Rhodes, J.J.; McCullough, D.A.; Espinosa, F.A., Jr. 1994. A coarse screening

process for evaluation of the effects of land management activities on salmon

spawning and rearing habitat in ESA consultations. Tech. Rep. 94-4. Portland,

OR: Columbia River Inter-Tribal Fish Commission. 127 p.

102
Robinson, P.T. 1975. Oregon: John Day Formation in the southwestern part of

the Blue Mountains and adjacent areas, north-central [Reconnaissance geologic].

I-872. Reston, VA: U.S. Department of the Interior, Geological Survey. 1:250,000;

colored.

Robinson, P.T.; Walker, G.W.; McKee, E.H. 1990. Eocene, Oligocene and lower

Miocene rocks of the Blue Mountains region. In: Walker, G.M., ed. Geology of the

Blue Mountains region of Oregon, Idaho, and Washington: Cenozoic geology of

the Blue Mountains region. Professional Pap. 1437. Washington, DC: U.S. Department of the Interior; U.S. Government Printing Office: 29-62.

Rosgen, D.L. 1985. A stream classification system. In: Johnson, R.R.; Ziebell,

C.D.; Palton, D.R. [and others], eds. Riparian ecosystems and their management: reconciling conflicting uses. In: Proceedings, 1st North American riparian

conference; 1985 April 16-18; Tucson, AZ. [Place of publication unknown]:

[Publisher unknown]: 91-95.

Sankela, W.E. 1937a. Forest statistics for Morrow County, Oregon. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and

Range Experiment Station. 6 p.

Sankela, W.E. 1937b. Forest statistics for Umatilla County, Oregon. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and

Range Experiment Station. 8 p.

Schuster, J.E. 1993. Clarkston Quadrangle, Washington-Idaho and the Washington

portion of the Orofino Quadrangle [Geologic]. [Place of publication unknown]:

Washington State Department of Natural Resources, Division of Geology and Earth

Resources. 1:100,000; open-file report 93-4. 43 p.

Schuster, J.E. 1994. Walla Walla Quadrangle, Washington [Geologic]. [Place of

publication unknown]: Washington State Department of Natural Resources,

Division of Geology and Earth Resources. 1:100,000; open-file report 94-3.

18 p.

Sedell, J.R.; Beschta, R.L. 1991. Bringing back the “bio” in bioengineering.

American Fisheries Society Symposium. 10: 160-175.

Sedell, J.R.; Bisson, P.A.; Swanson, F.J.; Gregory, S.V. 1988. What we know

about large trees that fall into streams and rivers. In: Maser, C.; Tarrant, R.F.;

Trappe, J.M.; Franklin, J.F., eds. From the forest to the sea: a story of fallen trees.

Gen. Tech. Rep. PNW-GTR-229. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research Station: 47-81.

Sedell, J.R.; Reeves, G.H.; Hauer, F.R. [and others]. 1990. Role of refugia in

recovery from disturbances: modern fragmented and disconnected river systems.

Environmental Management. 14(5): 711-724.

Smith, W.D.; Allen, J.E.; Staples, L.W.; Lowell, W.R. 1941. Geology and

physiography of the northern Wallowa Mountains, Oregon. Bull. 12. State of

Oregon, Department of Geology and Mineral Industries. 55 p.

103
Soil Conservation Society of America. 1982. Resource conservation glossary.

Ankeny, I A. 193 p.

Stanford, J.A.; Ward, J.V. 1992. Management of aquatic resources in large

catchments: recovery interactions between ecosystem connectivity and environmental disturbance. In: Naiman, R.J., ed. Watershed management: balancing

sustainability and environmental change, New York: Springer-Verlag: 91-124.

Sullivan, K.; Lisle, T.E.; Dolloff, C.A.; Reid, L.M. 1987. Stream channels: the link

between forests and fishes. Pacific Northwest forest landscapes. In: Salo, E.O.;

Cundy, T.W., eds. Streamside management: forestry and fishery interaction. No.

57. Seattle, WA: University of Washington: 39-97.

Swanson, F.J.; Benda, L.E.; Duncan, S.H. [and others]. 1987. Mass failures and

other processes of sediment production in Pacific Northwest forest landscapes. In:

Salo, E.O.; Cundy, T.W., eds. Streamside management: forestry and fishery

interaction. No. 57. Seattle, WA: University of Washington: 9-38.

Swanston, D.N. 1991. Natural processes. In: Meehan, W.R., ed. Influences of forest

and rangeland management on salmonid fishes and their habitats. Spec. Publ. 19.

Bethesda, MD: American Fisheries Society: 139-179.

Taubeneck, W.H. 1957. Geology of the Elkhorn Mountains, northeastern Oregon:

Bald Mountain batholith. Geological Society of America Bulletin. (75): 181-238.

Taylor, G. 1994. Oregon Climate Service: a new Oregon precipitation map. Oregon

Cursor. 7(1): 4, 10.

Thayer, T.P. 1990. The geologic setting of the John Day Country, Grant County,

Oregon. [Place of publication unknown]: Pacific Northwest Parks and Forests

Association. 23 p.

Thiele, S.A.; Kiilsgaard, C.; Omernik, J.M. 1992. The subdivision of the coast range

ecoregion of Oregon and Washington. Corvallis, OR: Environmental Protection

Agency, Environmental Research Laboratory. 39 p.

U.S. Department of Agriculture, Forest Service. 1936. The forest survey of

eastern Oregon and eastern Washington: explanatory text to accompany forest

statistics for each county. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Forest and Range Experiment Station. 8 p.

U.S. Department of Agriculture, Forest Service. 1949. Forest type classification of

the Pacific Northwest region. Portland, OR: Pacific Northwest Forest and Range

Experiment Station. 15 p.

U.S. Department of Agriculture, Forest Service. 1952. Forest type classification of

the Pacific Northwest region, revised. Portland, OR: Pacific Northwest Forest and

Range Experiment Station. 33 p.

U.S. Department of Agriculture, Forest Service. 1957. Plot procedure and forest

type classification. Portland, OR: Pacific Northwest Forest and Range Experiment

Station. 35 p.

104
U.S. Department of Agriculture, Soil Conservation Service. 1993. State soil

geographic data base (STATSGO). Misc. Publ. 1492. Washington, DC: U.S.

Government Printing Office. 88 p.

U.S. Department of the Interior, Bureau of Reclamation. 1985. Planning report

concluding the study of the Upper John Day project, Oregon. [Place of publication

unknown]: [Publisher unknown] 107 p.

U.S. Department of the Interior, Geological Survey. 1970. United States [potential

natural vegetation]. Washington, DC: Geological Survey. 1:7,500,000; colored; In:

The national atlas of the United States of America: 89-91.

U.S. Department of the Interior, Geological Survey. 1980. Washington and Idaho:

Columbia River Basalt Group, Pullman and Walla Walla Quadrangles, SE

Washington and adjacent Idaho. [Reconnaissance geologic]. 1-1139. Reston, VA:

1:250,000; colored.

U.S. Department of the Interior, Geological Survey. 1987. Digital elevation

models: data users guide 5. Reston, VA. 38 p.

U.S. Department of the Interior, Geological Survey. 1989. Digital line graphs from

1:100,000 scale maps: data users guide 2. Reston, VA.

[http://www-nmd.usgs.gov/www/html/2nmdgds.html].

Vannote, R.L; Minshall, G.W.; Cummins, K.W. [and others]. 1980. The river continuum concept. Canadian Journal of Fisheries and Aquatic Sciences. 37: 130-137.

Walker, G.W. 1973. Oregon and Washington: Pendleton quadrangle [Reconnaissance geologic]. Washington, DC: U.S. Department of the Interior, Geological

Survey. 1:250,000; colored.

Walker, G.W. 1979. Oregon: Grangeville quadrangle, Baker, Union, Umatilla and

Wallowa Counties [Reconnaissance geologic]. 1-1116. Reston, VA: U.S. Department of the Interior, Geological Survey. 1:250,000; Transverse mercator projection;

colored.

Walker, G.W. 1990a. Miocene and younger rocks of the Blue Mountains region

exclusive of the Columbia River Basalt Group and associated mafic lava flows.

In: Walker, G.M., ed. Geology of the Blue Mountains region of Oregon, Idaho,

and Washington: Cenozoic geology of the Blue Mountains region. Professional

Pap. 1437. Washington, DC: U.S. Government Printing Office: 101-118.

Walker, G.W. 1990b. Overview of the Cenozoic geology of the Blue Mountains

region. In: Walker, G.M., ed. Geology of the Blue Mountains region of Oregon,

Idaho, and Washington: Cenozoic geology of the Blue Mountains region.

Professional Pap. 1437. Washington, DC: U.S. Government Printing Office: 1-12.

Walker, G.W.; MacLeod, N.S. 1991. Oregon [Geologic]. Reston, VA: U.S.

Department of the Interior, Geological Survey. 1:500,000; Lambert conformal conic

projection; colored; 2 sheets.

105
Walker, G.W.; Robinson, P.T. 1990. Paleocene, Eocene, and Oligocene rocks of

the Blue Mountains region. In: Walker, G.M., ed. Geology of the Blue Mountains

region of Oregon, Idaho, and Washington: Cenozoic geology of the Blue

Mountains region. Professional Pap. 1437. Washington, DC: U.S. Department of

the Interior, Geological Survey; U.S. Government Printing Office: 13-28.

Warren, C.E. 1979. Toward classification and rationale for watershed management

and stream protection. EPA-600/3-79-059. Corvallis, OR: Environmental Protection

Agency. 143 p.

Water Resources Board. 1963. Umatilla River basin. Salem, OR: State of Oregon.

107 p.

Water Resources Department. 1988. Umatilla basin report. Salem, OR: State of

Oregon. 246 p.

Weissenborn, A.E., ed. 1969. Mineral and water resources of Oregon. Bull. 64.

Washington, DC: U.S. Government Printing Office; U.S. Department of the Interior,

Geological Survey. 469 p.

Whiteman, K.J.; Vaccaro, J.J.; Gonthier, J.B.; Bauer, H.H. 1994. The

hydrogeologic framework and geochemistry of the Columbia Plateau Aquifer

System, Washington, Oregon, and Idaho. Professional Pap. 1414-B. Washington,

DC: U.S. Department of the Interior, Geological Survey; U.S. Government Printing

Office. 73 p.

Whittier, T.R., Hughes, R.M.; Larsen, D.P. 1988. Correspondence between

ecoregions and spatial patterns in stream ecosystems in Oregon. Canadian

Journal Fisheries and Aquatic Sciences. 45: 1264-1278.

Williams, J.E.; Johnson, J.E.; Hendrickson, D.A. [and others]. 1989. Fishes of

North America endangered, threatened and of special concern. Fisheries. 14(6):

2-20.

Wissmar, R.C. 1993. The need for long-term stream monitoring programs in forest

ecosystems of the Pacific Northwest. Environmental Monitoring and Assessment.

26: 219-234.

Wissmar, R.C.; Swanson, F.J. 1990. Landscape disturbances and lotic ecotones.

In: Naiman, R.J.; Decamps, H., eds. The ecology and management of

aquatic-terrestrial ecotones, UNESCO Man and the Biosphere Series, Volume 4.

Paris, France: United Nations Education Scientific and Cultural Organization

(UNESCO): 65-89.

Wolfe, H.M. 1937. Forest statistics for Crook County, Oregon. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Forest and Range

Experiment Station. 8 p.

Woodward, F.I. 1987. Climate and plant distribution. Cambridge studies in ecology.

New York: Cambridge University Press. 174 p.

106
Acknowledgments Special thanks to the many providers of data. Many people provided draft data so

that we could get started on our project—Steve Beckwitt, Sierra Biodiversity Institute;

Susan Balikov, Wilderness Society; Gary Raines, USDI Geological Survey, University

of Nevada, Reno; Bruce Johnson and Pamela Derkey, USDI Geological Survey,

Spokane Field Office; Sue Pierson, Ogden; Marcia Brett, Oregon State University,

Crop and Soil Science Department; George Taylor, Oregon State University, State

Climatologist; Tom O’Neill and Milt Hill, Oregon Department of Fish and Wildlife;

Vi Agnew, USDA Forest Service, Pacific Northwest Region; Art Kreger and Anna

Kramer, USDA Forest Service, Wallowa-Whitman National Forest; David Powell, Keith

Walbridge, and Sean McKinney, USDA Forest Service, Umatilla National Forest;

Kelly Cassidy, University of Washington, Cooperative Fish and Wildlife Research Unit;

Sandra Bahr, Washington Department of Natural Resources; Jamie Kienzle, Natural

Resource Conservation Service, Wallowa County; and Robert Weinberger, Boise

Cascade.

The integration of source material from a wide range of disciplines was greatly aided

by several people familiar with the natural resources of the study area—Ellen Bishop,

Oregon Watershed Health Program; Mark Ferns and Bob Ottersberg, USDA Forest

Service, Wallowa-Whitman National Forest; Karl Hippie, Natural Resource Conservation Service, Washington; and Duane Lammers, USDA Forest Service, Pacific Northwest Region.

Technical assistance and project support for sections 1 and 2 were provided by

Sandi Azevedo, Francie Faure, Sue Pierson, and Marge Hails. Technical assistance

and project support for section 3 was provided competently and cheerfully by the

staff of the Aquatic/Land Interactions Program at the Pacific Northwest Research

Station in Corvallis, Oregon—Kelly Christiansen, Sudhi Gulur, Tami Lowry, Paula

Minear, Nathan Poage, Cathy Baldwin, Kathryn Ronnenberg, Sam Vedanayam, and

George Weaver.

The helpful comments of the many reviewers were greatly appreciated—Jim Omernik,

Corvallis, Environmental Protection Agency; Chip Andrus and Cynthia Chapman,

ManTech Environmental Research Services; Dan Bottom, Oregon Fish and Wildlife

Department; Paula Minear, Oregon State University, Fish and Wildlife Department;

Duane Lammers, USDA Forest Service, Pacific Northwest Region; Charlie Johnson,

Malheur, Umatilla, and Wallowa-Whitman National Forests; Ellen Bishop, Oregon

Watershed Health Program; Jonathan Rhodes, Columbia River Inter-Tribal Fish

Commission; and Gordie Reeves, USDA Forest Service, Pacific Northwest Research

Station.

Kelly Burnett and Duane Lammers of the USDA Forest Service, Pacific Northwest

Research Station and Glen Griffith of the Corvallis, Environmental Protection Agency

participated in many thoughtful discussions about the utility of the ecoregion

approach.

This document has been funded by the U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station through BPA Project Number 89-104 to

Oregon State University and U.S. Environmental Protection Agency National Health

and Environmental Effects Research Laboratory, Western Ecology Division, in

Corvallis, Oregon, through Contract 68-C4-0019 to ManTech Environmental Research

Services Corporation. It has been subjected to the EPA’s peer and administrative

review and approved for publication.

107
Clarke, Sharon E.; Bryce, Sandra A., eds. 1997. Hierarchical subdivisions of the

Columbia Plateau and Blue Mountains ecoregions, Oregon and Washington. Gen.

Tech. Rep. PNW-GTR-395. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station. 114 p.

This document presents two spatial scales-subregions (1:250,000) and landscapelevel ecoregions (1:100,000) of an hierarchical framework and provides a connection

to both larger and smaller scale ecological classifications. Two ecoregions—the

Columbia Plateau and the Blue Mountains—were subdivided by using a combination

of soils, topography, geology, vegetation, and climate. Subregions were developed to

meet the needs of state agencies for establishing biocriteria, reference sites, and

attainability goals for water-quality regulation. The finer scale landscape-level

ecoregions were developed to help local land managers address anadromous fish

habitat issues.

Keywords: Ecoregions, anadromous fish habitat, fish habitat, watershed classification,

landscape ecology, water quality, environmental mapping, classification.

The Forest Service of the U.S. Department of

Agriculture is dedicated to the principle of multiple

use management of the Nation’s forest resources

for sustained yields of wood, water, forage, wildlife,

and recreation. Through forestry research, cooperation with the States and private forest owners, and

management of the National Forests and National

Grasslands, it strives—as directed by Congress—to

provide increasingly greater service to a growing Nation.

The United States Department of Agriculture (USDA)

prohibits discrimination in its programs on the basis

of race, color, national origin, sex, religion, age, disability,

political beliefs, and marital or familial status. (Not all

prohibited bases apply to all programs.) Persons with

disabilities who require alternative means of communication of program information (Braille, large print, audiotape,

etc.) should contact the USDA’s TARGET Center at

(202) 720-2600 (voice and TDD).

To file a complaint, write the Secretary of Agriculture,

U.S. Department of Agriculture, Washington, DC 20250,

or call (800) 245-6340 (voice), or (202) 720-1127 (TDD).

USDA is an equal employment opportunity employer.

Pacific Northwest Research Station

333 S.W. First Avenue

P.O. Box 3890

Portland, Oregon 97208-3890
“In the original printed publication, color maps are contained in an envelope on this page.”

U.S. Department of Agriculture

Pacific Northwest Research Station

333 S.W. First Avenue

P.O. Box 3890

Portland, OR 97208

Official Business

Penalty for Private Use, $300

do NOT detach label

color maps ar

“In the original printed publication,

color maps are contained in an envelope on this page.”